phylogenetic analysis of the pinnotheridae (crustacea, brachyura) based on larval morphology, with...

Pergamon Zoologica Scripta, Vol. 24, No . 4, pp. 347-364, 1995

Elsevier Science Ltd 0 1995 The Norwegian Academy of Science and Letters

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Phylogenetic analysis of the Pinnotheridae (Crustacea, Brachyura) based on larval morphology, with emphasis on the Dissodactylus species corn plex

FERNANDO MARQUES and GERHARD POHLE

Accepted 6 June 1995

Marques, F. & Pohle, G. 1995. Phylogenetic analysis of the Pinnotheridae (Crustacea, Brachyura) based on larval morphology, with emphasis on the Dissodactylus species complex.-Zool. Scr. 24: 347-364.

Comparative larval morphology was used to elucidate phylogenetic relationships within the Pinnotheridae and the Dissodactylus species complex. Within the family, seven zoeal and six megalopal characters suggested two equally parsimonious phylogenetic hypotheses for pinnotherid larvae, both with Ostracotheres tridacnae representing the sister group for the Dissodactylus complex. Results indicated that the genus Pinnotheres is a polyphyletic taxon, and that the traditional subfamilial arrangement comprises paraphyletic taxa within the subfamilies Pinnotheri- nae and Pinnothereliinae. Certain evidence has suggested that Fabia and Juxtafubia should be excluded from the Pinnotherinae and placed into the Pinnothereliinae. Larval and adult morphology suggested that Pinnotherespolitus should be included within Tumidotheres. The phylogenetic analysis within the Dissodactylus complex involved one zoeal and 16 megalopal characters. Results suggested a single phylogenetic hypothesis based on larval morphology. Combining adult morphology with larval evidence resulted in two equally parsimonious phylogenetic hypotheses, one of which agreed with a previously suggested hypothesis based only on adult characters.

Fernando Marques, University of Toronto, Department of Zoology, Toronto, On tario, M5S IAI, Canada. Gerhard Pohle, A tlantic Reference Centre, Huntsman Marine Science Cen tre, St. Andrews, New Brunswick, EOG 2x0, Canada.

Introduction

“If, then, comparative anatomy enables us to trace from the study of the adults of an order, a family, or a genus their natural or genealogical classification, it must of course be possible to do the same thing with the larvae, and if the classification which is established is natural, there must be a discoverable relation between the one derived from larvae and the one derived from adults.” (Brooks 1886:15).

In the past two decades, larval morphology has received increasing attention from carcinologists as a potential source of characters which would help solve problems in brachyuran systematics. Attempts to use larval information for brachyuran systematics go back to the begin- ning of this century (Rice 1980). However, one major problem has been the scarcity of detailed descriptions of reliably identified larvae, and as a result, the number of available characters for analysis has been restricted. Only the relatively recent in-depth studies on Brachyura by Rice (1980,1981) have successfully demonstrated systematic relationships based on larval characters.

Rice (1980) used established adult classification as the basis for his analysis on zoeal morphology. Support for these groupings was sought in zoeal stages. Based on adults, he noticed that the more advanced brachyuran groups showed derived larval features related to the reduction in both setation and appendage segmentation

(Rice 1980). Thus, he postulated that reduction of segmentation and setation is an evolutionary trend within this group.

The objectives of the present analysis were: (i) to provide a preliminary hypothesis for the sister group relationships among known pinnotherid larvae; (ii) to compare the results of this analysis with the traditional systematics of the family; (iii) to postulate a sister group for the Dissodactylus species complex; (iv) to use the sister group to infer character polarity in the phylogenetic analysis within the Dissodactylus species complex; (v) to compare the results of the phylogenetic analysis based on larval characters to that based on adult ones by Griffith (1987b); and (vi) to combine the larval and adult information for a better understanding of the evolutionary history of the Dissodactylus complex.

Material and methods

Seven zoeal and six megalopal characters were used for the phylogenetic analysis of the family Pinnotheridae. The data were obtained from larval descriptions in the literature (see Table 111, Marques & Pohle in press a, b) and from specimens of four other species: Calyptraeotheres granti, Juxtafabia muliniarum , Fabia sp., and Pinnotheres angelicus. The analysis involved a total of 50 species, representing 17 genera and four subfamilies. Descriptions covering all stages were available only for 26

347 Zoologica Scripta 24

348 F. Marques and G. Pohle

Table I . The division of the genus Pinnotheres according to larval morphology, including the genus Tumidotheres and Zaops, formerly part of Pinnotheres (senuso lato). Within the group Pinnotheres I , P. boninensis ( A ) , P. aff. sinensis (B), and Zaops ostreum (C) have morphologically distinct types of megalopae

Group Species

Pinnotheres I

Pinnotheres 11

Pinnotheres 111

Pinnotheres placunae P. taylori P. angelicus

Pinnotheres boninensis (A) P. holothuriae P. latissimus P. novaezelandiae P. ridgewayi P. aff . sinensis (B) P. sinensis Zaops ostreum (C)

Pinnotheres politus Tumidotheres maculatus

Pinnotheres gracilis Pinnotheres hickmani P. modiolicola P. pholadis P. pisum P. vicajii

species. For the remaining species, only partial information, that is mostly restricted to the first zoea, was obtainable.

According to the phylogenetic school, the major objective of systematics is to search out shared advanced characters (synapomorphies) which can be used to define groups and subgroups (Nelson 1978). However, the most important theoretical issue of phylogenetic inference lies in the problem of polarity determination of character states of a homologous feature. The outgroup comparison (Watrous & Wheeler 1981; Maddison et al. 1984) is the most used method to infer polarity. As pointed out by Brooks & McLennan (1991), sometimes the outgroup comparison method alone does not allow polarization of character states, especially in cases of multistate transformation series. In this case, they suggest, other biological data such as developmental se- quences could be applied.

In the present study, two criteria were used to infer polarization within the family Pinnotheridae: Rice's criterion, as defined above, and Nelson's ontogenetic criterion, which assumes that, in an ontogenetic character transformation, from a character observed to be more general to a character observed to be less general, the more general character is plesiomorphic and the less general apomorphic (Nelson 1978). Although both criteria have theoretical problems (Nelson 1978; De Queiroz 1985; Kraus 1988), using these two criteria was considered to be more useful than utilizing an arbitrary outgroup since most of the characters used involved multistate transformation series.

The analysis within the family consisted of two steps. First, zoeal morphology, represented by characters 1-7, was considered. Assump- tions made to include as many taxa as possible were that, in Asthenog- nathus, the unknown state of character 3 is plesiomorphic and that the unknown state of character 4 was plesiomorphic for Xenophthalmus and Pseudopinnixa, and apomorphic in Calyptraeotheres, Juxtafabia and Pinnotheres angelicus. In addition, some species of Pinnotheres were united into three subgroups based on shared zoeal morphology. These groupings included two species, Zaops ostreum and Tumidotheres maculatus, formerly considered to belong to Pinnotheres (sensu lato). Three other species of Pinnotheres with distinct zoeae were represented separately (Table I).

The second step of the analysis consisted of incorporating data on megalopal morphology with those on zoeae. Taxa without information on megalopae, or with more than two unknown character states, were excluded from the analysis. Assumptions made in addition to those of the zoeal analysis include that, in Asthenognathus, the unknown state of characters 9 and 12 is plesiomorphic. In addition, the group Pinnotheres I was represented separately by three species with distinct megalopal morphology: Pinnotheres boninensis, P. affinis sinensis and Zaops ostreum, as Pinnotheres IA, Pinnotheres IB, and Pinnotheres IC, respectively (Table 1).

Using Rice's criterion, it was determined that Asthenognathus is the most basal genus within the family. Nelson's (1978) ontogenetic criterion was used as an auxiliary criterion in cases where a given transformation series did not include reduction of segmentation and/or

Zoologica Scripta 24

setation. The character transformation series were left unordered when Rice's (1981) and Nelson's (1978) arguments were not helpful to infer polarity (e.g. characters 5 , 6, 7 and 9).

The data used in the phylogenetic analysis of the Dissodactylus complex were obtained from eight publications (Pohlc & Tclford 1981, 1983; Pohle 1984, 1989, 1994; Marques & Pohle in press a , b ; Griffith 1987a). The analysis involved six species of the genus Dissodactylus (sensu stncto) and two species of Clypeasterophilus. The data matrix contained a total of 17 Characters, one from zoeal stagcs and 16 from the megalopa. The argumentation for each character transformation was made according to Maddison et al. (1984), based on the phylogenetic hypothesis for the pinnotherid larvae. Characters were left unordered if the decision regarding the character state at the outgroup node remained equivocal.

The computer program PAUP (Phylogenetic Analysis Using Parsi- mony, version 3.1.1, Swofford, 1993) was used to process the data matrix. The Branch-and-Bound algorithm was used for the analyses.

Results

Character analysis within the Pinnotheridae and sister group determination of the Dissodactylus species complex

1. Pinnotherid zoeae. Seven zoeal characters were used in the present analysis. The distribution of character states for the following characters among 50 different pinnotherid taxa is given in Table 11.

Character 1. First zoea: antenna1 morphology (Fig. 1A- E). Among pinnotherid zoeae, there are five types of antennae, designated as character states 1°-14. Type 1' is characterized by the presence of a protopodite and segmented endopodite (Fig. 1A). Type 1* differs from type 1" by having an unsegmented endopodite (Fig. 1B). Type l2 is characterized by the absence of the endopodite. The antenna consists of an elongate and uniramous tapered protopodite with two rows of spinules distally, and with or without a proximal seta (Fig. 1C). Type l 3 has a much reduced protopodite with a short process (Fig. 1D). Type l4 consists of an extremely reduced bud-like protopodite, or it is considered absent (Fig. 1E). By considering reduction as the more derived state, the transformation series 1°-14 was obtained.

Character 2. Zoeal stages: endopodite segmentation of the second maxilliped (Fig. 2A-C). Species with three, two and one segment were found. Those with three segments were considered to be the most plesiomorphic within the transformation series 2" , 2' and 22.

Character 3. Zoeal stages: endopodite setation of the maxilla (Fig. 3A-C). The setation on the endopodite of the maxilla ranges from three to five setae. Within the transformation series of five to three setae, five setae was considered to be the plesiomorphic condition in relation to four setae, and four setae was a plesiomorphic condition compared to three setae.

Character 4. Zoeal stages: number of abdominal somites (Fig. 4A,B). Within the family Pinnotheridae, there are some species with six abdominal somites present through- out zoeal development. Conversely, others have five somites. The loss of segmentation was considered as the derived condition.

Character 5. Zoeal stages: shape of the fifth abdominal somite (Fig. 5A-C). Three character states were determined, based on relative lateral expansion of this somite, but there is no evidence as to which state is more derived.

Pinnotherid phylogeny based on larval morphology 349

Table 11. States of 13 larval characters offifiy species of pinnotherids (see text and Figs 1-7 and 9-14 for character and character state definition)

Zoeal characters -

Species 1 2 3 4 5 6 7 8

Megalopal characters

9 10 11 12 13

Asihenognathus atlanticus 0 0 ? 0 0 0 0 0 ? 0 0' '? 0 Calyptraeotheres granii 2l 1 2 ? 0 1 0 ? ? ? ? ? ? Clypeasterophilus rugatus 2 1 2 1 0 1 0 0 0 1 2 I f I C. stebbingi 2 1 2 1 0 1 0 0 0 1 2 1 ' 1 Dissodaciylus crinitichelis 2 1 2 1 0 1 0 0 0 1 2 0' 1 D. lockingtoni 2 1 2 1 0 1 0 0 0 1 2 0' 1 D. melliiae 2 1 2 1 0 1 0 04 0 1 2 0' 0 D. nitidus 2 1 2 1 0 1 0 0 0 1 2 0' 1 D. primitivus 2 1 2 1 0 1 0 0 0 1 2 0' 1 D. xantusi 2 1 2 1 0 1 0 0 0 1 2 0' 1 Epuloiheres chamue 4 1 2 1 0 4 314' O4 0 1 2 ? I E. moseri ?4 ? ? 1 0 4 3 ? ? ? ? Fabia sp. 2 1 2 ? 2 32 0 ? ? '? '? ? ? F. subquadrata 2 1 ? 1 2 2 0 ? ? O 2 ? '? Juxtafabia muliniarum 2 1 2 ? 2 2 0 ? ? <? ? ,? ? Nepinnotheres pinnotheres 4l 1 2 1 0 4 0 ? ? I 2 0' 0

2'' 1 Ostracotheres iridacnae 2 2 2 1 0 4 0 04 0 1 3 Parapinnixa afjinis 4?' O?' ? ? 2?' 2/3?' 3 ? ? ? ? ? ? Pinnaxodes chilensis 2 1 2 ? O 1 0 ? ? ? ? ? '? P. major 2l 1 2 0 0 1 0 0 0 0 0 0 0 P. muiuensis 2 1 2 0 0 1 0 1 1 1' 0 0 0 Pinnixa chaetopterana 2' 1 ? ? 2 3 0 ? ? ? ? ? ? P. cristaia 2' 1 ? ? 2 3 0 ? ? ? ? ? ? P. cylindrica 2l 1 ? ? 2 2 0 ? ? ? ? ? ? P. longipes 2I 1 2 1 2 2 0 1 1 1 0 0' 0 P. raihbuni 2l 1 2 1 2 2 0 I 1 1 0 0 0 P. aff . raihbuni 2' 1 2 1 2 2 0 1 1 1 0 07' 0 P. sayana 2' 1 ? ? 2 2 0 ? ? ? ? ? ? Pinnoiheres angelicus 4 1 2 ? 0 4 1 ? ? ? '? 7 ? P. boninensis 4 1 2 1 0 4 4 0(1?) 1 1 2 I f 0 P. gracilis 4 1 2 1 0 4 2 1 1 1 2 2' 0

? ? P. hickmani ? ? ? 1 0 4 2 ? ? ? ? ? ? P. holoihuriae ~ 4'? ? ? 1 0 4 4 ? ? ? ?

P. latissimus 4 1 ? 1 0 4 4 ? ? ? ? ? ? P. modiolicola 4l 1 2 1 0 4 2 ? ? ? ? ? ? P. novaezelandiae ? ? ? 1 0 4 4 ? ? ? ? ,? ? P. pholadis 4' 1 2 1 0 4 2 ? ? ? ? ? ? P. pisum 4I 1 2 1 0 4 2 ? ? I ? 2' 0 P. placunae 2 1 2 1 0 4 2 ? ? ? ? ? ? P. politus 2 1 2 0 0 1 0 0 1 0 0 I' 0 P. ridgewayi 4 1 2 1 0 4 4 ? ? ? ? ? 1

P . sinensis 4' 1 2 1 0 4 4 ? ? ? ? '? ? P. aff . sinensis 4l 1 2 1 0 4 4 1 1 1' 2 2' 1 P. taylori 3 1 2 1 0 1 5 1 1 1 1 ? 0 P. vicajii 4l Id ? 1 0 4 2 ? ? ? ? ? ? Pseudopinnixa carinaia 2l 1 1 ? 0 0 0 ? ? ? '? ? ? Sakaina japonica 2 0 1 0 2 1 3 0 0 0 2 0 0 Tumidoiheres maculaius 2 1 2 0 0 1 0 0 1 0 0 1 0 Xenophihalmus garihii 1 0 0 ? 1 1 0 ? ? ? ? ? ? Zaops osireum 4 1 2 1 0 4 4 ? ? 1 211" 0' 0

? 7

' = character state taken from figure; = seta also present; ' = median projection much smaller than lobe in some Pinnixa spp.; = type 3 in zoea 1, type 4 in zoea 2; = dactyl absent, considered "0"; = single subterminal seta may be present; ' = text indicates

five segments, figure shows six.

Rice's criterion is not applicable here, and there is also no ontogenetic information which would suggest any polarization for the transformation. Therefore, the character was left unordered for analysis.

Character 6. Zoeal stages: shape of the telson (Fig. 6A- E). Five types of telsons were found among pinnotherid zoeae. Type 6" (Fig. 6A) is bifurcated and elongated. Its furcal shafts are very long, about 2/3 or more of the telson's length. Type 6l (Fig. 6B) is also bifurcated and elongated but the furcal shafts are less developed, representing 1/2 or less of the total length of the telson. In type 6* (Fig. 6C), the whole telson is more compact and not as elongated as in type 6'. Type 63 (Fig. 6D) differs from type 6' by the presence of a median projection on the furcal arch. Type 64 (Fig. 6E) is also somewhat rounded,

but the furcal shafts are greatly reduced to the size of the median projection found in the telson type 63.

During the zoeal development of Pinnixa cristata and P. chaetopterana, a type 6' telson, without a median projection, precedes a type 63 with a median process. Thus, according to Nelson's ontogenetic criterion, type 63 might be derived from a telson like type 6*. However, the relation between the transformation series 6' + 63 with the other character states cannot be inferred from either Nelson's or Rice's arguments. Thus, the character was left unordered for analysis.

Character 7. Zoeal stages: spines on the carapace (Fig. 7) . Within the Pinnotheridae, many kinds of combinations of carapace spines are found. Carapace type 7" includes dorsal, rostra1 and lateral spines. In carapace



A

h D

B

& E

L! C

A I----I

B C A D

w E

I-

Fig. 1.-A-E. Character 1 . Types of antennae present within the Pinnotheridae and hypothetical transformation series of five character states.-A. Xenophthalmus garthii (from Sankarankutty 1970).--B. Pseudopinnixa carinata (from Muraoka 1985).-C. Pinnotheres politus (from Saelzer & Hapette 1986).-D. Pinnotheres taylori (from Hart 1935).--E. Pinnotheres a f f . sinensis (from Yatsuzuka & Iwasaki 1979). Scale bars = 0.05 mm.

,, ,

Fig. 2.-A-C. Character 2. Second maxillipeds found in pinnotherid zoeae.-A. Sakaina japonica (three-segmented endopodite) (from Konishi 1983).--B. Clypeasterophilus rugatus (two-segmented endopodite) (from Pohle 1984).-C. Ostracotheres tridacnae (one-segmented cndopodite) (from Gohar & Al-Kholy 1957). Scale bars = 0.2 mm.

Fig 3.-A-C. Character 3. Types of setation and resulting transformation series of the maxillary endopodite in pinnotherid zoeae.-A. Xenophthalmus garthii (five setae) (from Sankarankutty 1970).--8. Sakaina japonica (four setae) (from Konishi 1983).-C. Dissoductylus nitidus (three setae) (from Pohle 1989). Scale bars = 0.1 mm.

Zoologica S c r i p 24

Pinnotherid phylogeny based on larval morphology 351 g .I :

I I A

B I- I

Fig. 4.-A-B. Character 4. Presence and absence of the sixth abdominal somite in zoeal development of the Pinnotheridae.-A. Asthenognuthus aflanficus (present) (from Bocquet 1965).-B. Dissodactylus primifivus (absent) (from Pohle & Telford 1983). Scale bars = 0.1 mm.

A -1

B t-------l

t-

i C

__I

Fig. 5.-A-C. Character 5. Expansion of the fifth abdominal somite in some genera of Pinnotheridae.-A. Dissodactylus nifidus (no expansion) (from Pohle 1989).-B. Xenophthalmus gurfhii (some expansion) (from Sankarankutty 1970).--C. Pinnixu Zongipes (fully expanded) (from Bousquette 1980). Scale bars = 0.2 mm.

type 7*, the dorsal spine is extremely reduced. Carapace type 72 displays only rostral and lateral spines. In carapace type 7’, only a rostra1 spine is present. Carapace type 74 lacks spines and carapace type 75 displays only the dorsal and rostral spines. Other possible combinations of spines, such as a carapace with only a lateral or dorsal spine, or with lateral and dorsal spines, are unknown within pinnotherid zoeae. This suggests a possible sequence or order of spine reduction. Thus, instead of considering each spine as a separate character, each carapace type was regarded as a character state. Ontogenetic information from Epulotheres chamae, which has a short rostral spine that is no longer present in the second zoea, would suggest partial polarization for this character. However, the polarization of the whole transformation series cannot be inferred from this ontogenetic information. Thus, the character was left unordered during the analysis.

The phylogenetic analysis of these data sets using the Branch-and-Bound search generated over 1400 equally parsimonious trees. Using the 50% majority rule and the Strict Consensus method resulted in the trees shown in Fig. 8.

2. Pinnotherid zoeae and megalopae. In the following analysis, six megalopal characters were added to the previous data set. The distribution of character states for the following characters among 50 different pinnotherid taxa is given in Table I1 under characters 8-13.

Character 8. Megalopa: insertion of the dactyl on the third maxilliped (Fig. 9A, B). The dactyl of the third maxilliped can be inserted terminally or subterminally within the Pinnotheridae. Hong (1974) showed that, in Pinnaxodes major, the dactyl is inserted terminally (Fig. 9A) in the megalopa, in contrast to subterminally in the first crab (Fig. 9B). Thus, with a terminal insertion pre- ceding the subterminal insertion during ontogeny, a terminally inserted dactyl would be considered as the plesiomorphic condition according to Nelson’s criterion.

Character 9. Megalopa: insertion of the dactyl on the second maxilliped (Fig. 10A, B). As in the third maxilliped, the dactyl can be found inserted terminally or subterminally on the propodus of the second maxilliped. However, there is no ontogenetic evidence that terminal insertion precedes subterminal insertion for this appendage. Therefore, the character was left unordered during the analysis.

Character 10. Megalopa: setation of the dactyl of the last ambulatory leg (Fig. ZlA, B). In megalopae of some pinnotherid species, the dactyl bears three setae terminally. Other megalopae do not have such setation. Reduction of setation was considered as the derived condition.

Character 11. Megalopa: segmentation of the antenna (Fig. 12A-D). There are species in which the antenna is seven-, six-, five- or three-segmented. Reduction of segmentation was considered to be the derived condition in the transformation series l1°-l13.

Character 12. Megalopa: segmentation of the outer ramus of antennules (Fig. 13A-C). There are species in which the outer ramus of the antennules is four-, three- or unsegmented. Reduction of segmentation was regarded as the apomorphic condition.

Character 13. Megalopa: segmentation of the inner ramus of antennules (Fig. 14A, B). There are species in which the inner ramus of the antennule is two or unsegmented. Reduction of segmentation was considered as being apomorphic.

The phylogenetic analysis of these data, suggesting hypothetical sister-group relationships for the family Pin- notheridae based on larval characters, resulted in two equally parsimonious trees, requiring 44 steps and having a consistency index of 71.1% (Fig. 15A,B). These cladograms differed only in the sister group relationships among representatives of Pinnotheres I (Pinnotheres boninensis IA, P . aft. sinensis IB), and Pinnotheres 111. Both cladograms indicated that Ostracotheres tridacnae was the sister group of the Dissodactylus complex.

Character analysis within the Dissodactylus species com-

Zoologica Scrip ta 24


E

I A

I- B

-1 C, D

E I I

I-

Fig. 6.-A-E. Character 6. Types of telsons found within the Pinnotheridae zoeae.-A. Asthenognuthus atlanticus (from Bocquet 1965).--8. Dissodactylus nitidus (from Pohle 1989).-C. Pinnixa longipes (from Bousquette 1980).-D. P. chaetopterana (from Dowds 1980).--E. Epulotheres chamae (from Roberts 1975). Scale bars = 0.1 mm.

Fig. 7. Character 7. Diagrammatic representation of carapace types found within the Pinnotheridae and respective character states

plex. In the following analysis, one zoeal and 16 megalopal characters were polarized as shown below, according to the outgroup method of Maddison et al. (1984), and with Ostracotheres tridacnae as the sister group of the Dissodactylus complex. The argumentation of the character polarization was based on the topology of the phylogenetic hypothesis for the pinnotherid larvae (Fig. 15A, B). Ostracotheres tridacnae represents the character state common to the family, unless stated otherwise. The distribution of character states for the following characters among the Dissodactylus complex species is given in Table 111.

Character 1. Zoeal stages: dorsolateral spines on the third abdominal somite (Fig. 16A, B). Within the Disso- dactylus complex, there are species with and without this

Zoologica S c r i p 24

feature. In 0. tridacnae, the dorsal spine is present indicating that, within the ingroup, the absence of the spine is apomorphic within the Dissodactylus complex.

Character 2. Megalopa: setation of the last antenna1 segment (Fig. 17A, B). Within the Dissodactylus complex, Clypeasterophilus has two setae but Dissodactylus (sensu stricto) only one seta. Ostracotheres tridacnae bears two setae on the last segment of the antenna. Thus, the outgroup comparison suggested that the reduction in the number of setae represents the apomorphic condition.

Character 3. Megalopa: segmentation of the outer ramus of antennules (Fig. 17A, B). Within the ingroup, both a four- and three-segmented outer ramus are present. The larval description of 0. tridacnae is unclear in this regard,


Asthenognathus Xenophthalmus Sakaina Parapinnixa Pseudopinnixa Pinmodes Pinnotheres I1 Calyptraeotheres Dissodacfylus complex Ostracotheres P. placunae P. taylori Fllbkl Pinnixa Juxtafabia Pinnotheres I11 Epulotheres Nepinnotheres P. angelicus Pinnotheres I

/= Asthenognathus (Asthenognathinae) Xenophthalmus (Xenophthalminae)

(Pinnotherinae) Parapinnma Pseudopinnixa (Pinnothereliae) Pinnaxodes

Calyptraeotheres Dissodacrylus complex Ostracotheres (Pinnotherinae)

P. placunae P. taylori Fabia Pinnixa (Pinnothereliinae) Juxtafabia Pinnot h e r e s 4 Epulotheres (finothejnae) Nepinnotheres P. angelicus Pinnotheres I

Fig. 8. Sister group relationships within the Pinnotheridae based on zocal characters and the traditional arrangement of the subfamilies within the Pinnotheridae. A, strict consensus tree; B, 50% majority rule consensus tree.

Fig. 9.-A-B. Character 8 . Insertion of the dactyl on the third maxilliped in the Pinnotheridae.-A. megalopa of Pinnaxodes major (terminal insertion) (from Hong 1974).-B. first crab of P. major (subterminal insertion) (from Hong 1974). Setation pattern was omitted. Scale bars = 0.1 mm.

as well as in other members of the family. Therefore, the polarity decision remained equivocal on the outgroup node, and the characters were considered unordered during the analysis.

Character 4. Megalopa: aesthetascs on the antennules (Fig. 17A, B). Within the Dissodactylus complex, species with six and four aesthetascs are present. In 0. tridacnae, there are eight setae. Outside the outgroup node, the taxa have six or more aesthetascs on the antennules, suggesting that reduction of the numbers of aesthetascs is a derived character within the Dissodactylus complex.

Character 5. Megalopa: segments on the inner ramus of antennules (Fig. 17A-D). Within the Dissodactylus complex, the character varies from two-segmented to vestigial. The character state is unclear for 0. tridacnae. Within the Pinnotheridae, this character is highly diverse. Despite such diversity, the polarization of the character transformation series within the ingroup was not possible. Therefore, the character was left unordered during the analysis, and coded as follows: 5', two-segmented endopodite (Fig. 17B); 5 ' , unsegmented endopodite (Fig. 17A); 5', reduced endopodite (Fig. 17C); and 53, vestigial endopodite (Fig. 17D).

Character 6. Megalopa: setation on the mandible (Fig. 18A, D). According to available information, Ostracoth- eres tridacnae and taxa below the outgroup node do not bear setae on the mandible. Thus, the presence of setae on the mandible was considered to be a derived character.

Character 7. Megalopa: mandibularpalp (Fig. 18A-D). In the Dissodactylus complex, the character ranges from a two-segmented palp bearing setae to a naked, unsegmented palp. In the sister group, the palp is three- segmented, bearing seven setae. Moreover, as in character 5 , there is variability within the taxa below the sister group. Therefore, the character was left unordered during the analysis, and coded as follows: 7(), two-segmented palp bearing setae (Fig. 18A); 7', two-segmented palp that is usually naked (Fig. 18B); 7', weakly bisegmented reduced and naked palp (Fig. 18C); and 73, unsegmented palp (Fig. 1SD).

Character 8. Megalopa: proximal seta on coxal endite of the maxillule (Fig. 19A, B). The proximal coxal seta may be present or absent within the Dissodactylus complex. However, in 0. tridacnae, the seta is missing, suggesting that the presence of the seta was a derived character within the ingroup.

Character 9. Megalopa: medial seta adjacent to the base of the scaphognathite (Fig. 20A, B). Within the Dissodac- tylus complex, the seta may be present or absent. The seta is absent in the sister group and below the outgroup node. Thus, the presence of the seta was considered to be derived within the Dissodactylus complex.

Character 10. Megalopa: setation of the exopodite of the first maxilliped (Fig. 21A, B). Within the Dissodactylus complex, there are species bearing one or two setae. Within the outgroup, Ostracotheres tridacnae bears two setae, suggesting that the presence of two or more setae is the plesiomorphic condition within the ingroup.

Character 11. Megalopa: medial seta on the epipodite of the first maxilliped (Fig. 21A-C). Within the ingroup, there are species with and without a medial seta. In the sister group, the character is unknown, and this is also the



I I

Fig. 10.-A-B. Character 9. Insertion of the dactyl on the second maxilliped in pinnotherid mega1opae.-A. Dissodactylus nitidus (terminal insertion) (from Pohle 1989).-B. Tumidotheres maculatus (subterminal insertion) (from Costlow & Bookhout 1966). Setation pattern of the endopodite was omitted. Scale bars = 0.1 mm.

Fig. 11.-A-B. Character 10. Setation patterns on the last ambulatory leg of pinnotherid megalopae.-A. Pinnotheres politus (dactyl with terminal setae) (from Saelzer & Hapette 1986).-B. Dissodactylus nitidus (dactyl without terminal setae) (from Pohle 1989). Scale bars = 0.1 mm.

case for most of the taxa below the outgroup node. Therefore, the character was left unordered during the analysis, and coded as follows: 1l0, absence of seta; 111, presence of seta.

Character 12. Megalopa: shape of the third maxilliped (Fig. 22A, B). Within the Dissodactylus complex, there are species in which the ischio-merus of the third maxilliped is sub-triangular, whereas in others it is sub- rectangular. In Ostracotheres tridacnae, the ischio-merus is sub-rectangular, suggesting that a sub-triangular ischio- merus represents the derived condition.

Character 13. Megalopa: dactyl of the third maxilliped (Fig. 22A-D). Within the ingroup, dactyl development ranged from well developed to absent, and from bearing two setae to being naked. In the sister group, the dactyl is absent. However, for other taxa within the family, the dactyl of the third maxilliped varies from absent to two- segmented and bearing more than 10 setae. Since a polarity decision was equivocal at the outgroup node, the character was left unordered and coded as follows: 13', dactyl well developed bearing two setae (Fig. 22A); 13l, dactyl reduced in size and may bear one seta (Fig. 22B); 132, dactyl greatly reduced and naked (Fig. 22C); and 133, dactyl absent (Fig. 22D).

Character 14. Megalopa: setation on the m e w s of the last ambulatory leg (Fig. 23A, B). Within the ingroup, a very long aesthetasc-like seta may be present or not. Ostra- cotheres tridacnae does not have this seta, and none of the

Zoologica Scrip f a 24

known pinnotherid megalopae has that feature. Thus, the outgroup method suggested that the presence of the aesthetasc-like seta was considered to be the derived condition within the Dissodactylus species complex.

Character 15. Megalopa: serrate setae on the dactyl of the cheliped (Fig. 24A, B). With the exception of the Dissodactylus complex, larval descriptions of 0. tridacnae and other pinnotherids do not provide specific information on setal types on this appendage. Therefore, the character was left unordered during the analysis and coded as follows: 15", absent; and 15l, present.

Character 16. Megalopa: serrate setae on the propodus of the cheliped (Fig. 24A, B). As for character 15, there is no specific account of this setal character within the Pinnotheridae other than for the Dissodactylus complex. Thus, the character was left unordered as well, and coded as follows: 16", absent; and 16l, present.

Character 17. Megalopa: setation on the posterior border of the sternum (Fig. 25A, B). There was no information for this character in 0. tridacnae. The same is valid for other members of the family. Therefore, the character was left unordered during the analysis, and coded as follows: 17', absent; and 17*, present.

Phylogenetic analysis of these data resulted in a single tree which suggested the hypothetical sister-group relationships for the known larvae of the Dissodactylus species complex (Fig. 26). The tree required a total of 32 steps and had a consistency index of 72%.

Combined larval and adult character analysis within the Dissodactylus species complex. The characters used by Griffith (19876) were combined with the larval information of the present study to provide a phylogenetic hypothesis which would include both larval and adult morphology. A data matrix summarizing the character states for larval and adult characters 1-36, with Griffith's characters starting at 18, is given in Table 111. Of the 28 adult characters used by Griffith (1987b), characters 4,5, 9,17,20-23 and 25 were excluded from the analysis since they were uninformative. Thus, a total of 36 larval and adult characters were used to evaluate 135, 135 trees, resulting in two equally parsimonious phylogenetic hypotheses, each requiring 57 steps and having a consistency index of 75% (Fig. 27).


A B C D Fig. 12.-A-D. Character 11. Antenna1 segmentation in pinnotherid mega1opae.-A. Pinnaxodes major (seven-segmented) (from Hong 1974).- B. Pinnotheres afinis sinensis (six-segmented) (from Yatsuzuka & Iwasaki 1979).-C. P . tuylori (five-segmented) (from Hart 1935).-D. Ostracotheres tridacnae (three-segmented) (from Gohar & Al-Kholy 1957). Scale bars = 0.1 mm.

B

A Fig. 13.-A-C. Character 12. Segmentation of the outer ramus of the antennule in pinnotherid mega1opae.-A. Pinnaxodes major (four- segmented) (from Hong 1974) .-B. Clypeasterophifus rugatus (three-segmented) (from Pohle 1984) .-C. Pinnotheres pisum (unsegmented) (from Atkins 1955). Scale bars = 0.1 mm.

w Discussion

Sister group relationships within the Pinnotheridae

Although the analysis of zoeal characters did not generate a single tree for the sister group relationships among the pinnotherid zoeae, the consensus trees indicated agreement in some relationships (Fig. 8A, B). The strict consensus tree (Fig. 8A) excludes Asthenognathus and Xenophthalmus from the node C which grouped most of the other pinnotherids. The genera Fabia, Juxtafabia and Pinnixa formed a monophyletic subgroup within the the node C. The tree based on the 50% maioritv rule (Fig. * , \ -

Fig. 14.-A-B. Character 13. Segmentation of the inner ramus of the antennule in pinnotherid mega1opae.-A. Pinnaxodes mutuensis (two-

rnented) (from Pohle 1989). Scale bars = 0.1 mm.

8B) partially resolved the polytomy of the node C in the segmented) (from Konishi 1981a).-B. D i s s o d a c t y ~ ~ nitidus (unseg- tree, suggesting that Sakaina and para-

pinnixa are sister taxa for 81% of the trees generated (Fig.



Asthen. S&im P W . Pinn. I1 P i n n k P. ray). , v c P ~ . P i m . IC Pinn.18 Pinn. [I1 Pi-. IA Epdoih. D. complex O-amtAbe

A

Anlun. S a b k P h a w d . PIM. 11 P i n n b P. tnyl. Nrpim. P i M . IC Pinn. IA P i ~ . l I l Pinn.IB Epuloth. D. complex Omamthwe

B

Fig. 15.-A-B. The two most parsimonious cladograms summarizing the sister group relationships among the known larvae of Pinnotheridae (numbers indicate characters; small superscripts states for a given character.

8B). Asthenognuthus and Sakaina remained as paraphyletic taxa when megalopal data were added (Fig. 15A, B). In the 50% consensus tree (Fig. 8B), Pseudopinnixa represented a separate clade at node D, and Pinnaxodes, Pinnotheres I1 and the ancestor of the node F formed a trichotomy at node E in 81% of the trees. The latter trichotomy was resolved with megalopal data (Fig. 15A, B), suggesting that Pinnaxodes and Pinnotheres I1 are


paraphyletic taxa. The polytomy of node F of the 50% consensus tree (Fig. 8B) was also further resolved by the addition of megalopal data. Thus, the taxa Pinnixa and Pinnotheres taylori are paraphyletic in relation to each other and to Pinnotheres 11 (Fig. 15A, B). Also, the Dissodactylus complex and Ostracotheres tridacnae are now sister groups. Likewise, node G of the 50"/0 consensus tree (Fig. 8B) was better resolved when megalopal


Y

A -1

B

Fig. 26.-A-B. Character 1. Spination of the third abdominal somite within the Dissodactylus complex.-A. Dissodactylus nitidus (dorsolat- era1 spine present) (from Pohle 1989).-B. Clypeasterophilus stebbingi (dorsolateral spine absent) (from Marques & Pohle in press a) . Scale bars = 0.1 mm.

data were included. According to the first tree (Fig. 15A), Pinnotheres a f f . sinensis and Pinnotheres gracilis (Pin- notheres IB and 111, respectively) form a monophyletic group paraphyletic to Zaops ostreum (Pinnotheres IC) and P. boninensis (Pinnotheres IA). The second tree (Fig. 15B) did not suggest any distinct monophyletic group, all taxa being paraphyletic in relation to each other.

Implications of the phylogenetic analysis on classic systematics of the family Pinnotheridae. The general consensus among carcinologists experienced with Pinnotheres (sensu lato) is that the genus is poorly understood taxono- mically (Manning pers. comm.). This was corroborated by the present larval study, as shown by the distinct groupings based on zoeal morphology (Table I). The group Pinnotheres I1 includes the two genera Pinnotheres and Tumidotheres, represented by P. politus and T. maculatus, respectively. Larval morphology suggested that Pinnotheres politus should be excluded from Pin- notheres (sensu stricto) . Using adult characters, Campos (1989) erected the genus Tumidotheres to include the type species Pinnotheres margarita Smith, 1869 from the East Pacific, and P. maculatus Say, 1818, from the western Atlantic. Campos gave the following diagnosis for the new genus: (i) carapace suborbicular and broader than longer; (ii) gastric and cardiac regions separated from branchiohepatic area by depressions; (iii) third maxilliped with ischium and merus fused; (iv) palp in three articles; (v) dactyl of the third maxilliped narrowly spatu- late; (vi) dactyl inserted in angular notch in the middle of ventral margin of the propodus; and (vii) abdomen seven- segmented in both sexes. Adults of Pinnotheres politus (Rathbun 1918: 71, fig. 5 ) differ from Tumidotheres only by a “thin and yielding, naked” carapace, which in the latter is “thick and firm but not hard; surface covered with short, dense, and deciduous tomentum”. The examin- ation of one adult female (USNM 40.448) of Pinnotheres politus showed that the diagnostic characters (vi) and (vii) of Campos for Tumidotheres are also present in P. politus. In addition, Christensen & McDermott (1958) showed that the carapace of Pinnotheres (sensu lato) undergoes distinct changes during post-larval development. This would likely affect the diagnostic characters of the carapace which do not agree between Tumidotheres and P.

politus. In conclusion, larval and adult morphology suggested that Pinnotheres politus is more likely to be included within Tumidotheres than Pinnotheres (sensu stricto).

There is less agreement between larval and adult morphology for members of the larval groups Pinnotheres I and 111. Pinnotheres I includes the genera Pinnotheres and the re-established Zaops (Manning 1993~) . The genus Zaops is represented by 2. ostreum, formerly within Pinnotheres. In adults of Z . ostreum, the palp of the third maxilliped is three-segmented, and the dactyl is inserted subterminally on the propodus (Rathbun 1918), as in Pinnotheres novaezelandiae of Pinnotheres I (Pregenzer 1979). However, in this regard, the third maxilliped in adults of Pinnotheres pisum, P. hickmani, and P. vicajii of Pinnotheres I11 is the same as for species of Pinnotheres I. While scored characters for zoeae in species of Pinnoth- eres I were identical, there were three distinct megalopal morphotypes, suggesting that this group may have separated further. The larval criterion separating Pinnotheres I and Pinnotheres I11 is spination of the zoeal carapace (Table 11, and Fig. 7), with data from megalopae lacking, or too poor to be useful. Considering the diversity in carapace spination among pinnotherids, it is not unlikely that reduction in carapace spination occurred more than once within species arranged into these groups. Addi- tional megalopal information may allow further phylogenetic conclusions for these species in the future. While it is too soon to assign species of Pinnotheres I into separate genera, it is likely that they, along with the four separately listed species (Table I), belong to new or different genera, not including Pinnotheres. The ex- clusion of species from Pinnotheres has already occurred in several instances (Manning 1993a, b; Campos 1989). Whether species assigned to group I11 together with Pinnotheres pisum, the designated type for the genus, can be kept within this genus cannot be ascertained without further evidence, such as from megalopae.

Another contradiction between the cladograms obtained in the present study and established pinnotherid taxonomy concerns subfamilial groupings (Fig. 8A, B) by Tesch (1918) and Schmitt et al. (1973). Tesch separated genera into the Pinnotherinae De Haan, 1833; Xenoph- thalminae Alcock, 1900; Pinnothereliinae Alcock, 1900; and Asthenognathinae Stimpson, 1856. Schmitt et al. (1973) also included the subfamily Anomalifrontinae Rathbun, 1931, and added more genera to Tesch’s list. Tesch (1918) acknowledged that it “is difficult to give a common diagnostic for this family” and that it is only “on the shape of these (third) maxillipeds that the four subfamilies are founded”. In the present study, the Anomali- frontinae was not represented due to the lack of larval descriptions. Larval morphology did suggest that the subfamily Asthenognathinae is the most basal subfamily within the Pinnotheridae, followed by the Xenophthalmi- nae. The strict consensus tree did not resolve sister group realtionships among the Pinnotherinae and Pinnotherelii- nae, whereas the 50% consensus tree indicated that the subfamilies Pinnotherinae and Pinnothereliinae are sub- divided into three and two subgroups, respectively (Fig. 8A, B). However, both the strict consensus and the 50% consensus trees suggested that Fabia and Juxtafabia

Znolngica Srripta 24


Fig. I7.-A-D. Characters 2-5. Segmentation and setation on the antenna and antennule within the Dissodactylus complex.-A. Clypeasferophilus rugatus (from Pohle 1984).--B. Dissodactylus mellifae (from Marques & Pohle in press b).-C. D. nitidus (from Pohle 1989).--0. D. xantusi (from Pohle, 1994). Scale bars = 0.1 mm.

should be excluded from the Pinnotherinae and placed into the Pinnothereliinae with Pinnixa, since they formed a monophyletic group (Fig. 8A, B). The 50% consensus tree (Fig. 8B) suggested that the Pinnotherinae, represented by Sakaina, Parapinnixa, Pinnaxodes, Calyptraeotheres, the Dissodactylus complex, Ostracotheres, Fabia, Juxta- fabia, Epulotheres, Nepinnotheres, and Pinnotheres (sensu lato), consists of paraphyletic taxa. This was corroborated by megalopal morphology (Fig. 15A, B). There- fore, this subfamily appears to be an artificial taxonomic group. The same is true for the subfamily Pinnotherelii- nae, suggesting that Pseudopinnixa should be excluded.

The results of the present study are not sufficient to

Zoologica Scrip fa 24

redefine the traditional pinnotherid subfamily arrangement due to the sparse representation of genera included in this larval analysis. However, as a result of this analysis, a hypothesis for sister group relationships within the Pinnotheridae can now be tested. Larval characters appear to be a useful tool in systematic studies and thus should be included to define taxonomic groups.

Sister group relationships within the Dissodactylus species complex

The tree based on larval characters (Fig. 26) suggested that D. nitidus and D. xantusi are each other’s closest


Griffith’s cladogram also suggested that D . crinitichelis is more closely related to D . mellitae than to D . primitivus, and that they share common exclusive ancestry. Larval evidence suggested that D . crinitichelis is more closely related to D . primitivus, and that there is no common ancestry for D . crinitichelis, D . mellitae, and D . primitivus as suggested by adult morphology (Griffith 19876).

7l

Combined larval and adult character analysis of the Disso- dactylus species complex: towards a better phylogenetic hypothesis. In Griffith’s (19876) cladistic analysis based on adult morphology, the genera Sakaina and Parapin- nixa were considered to be the sister group of the Disso- dactylus complex. Griffith found that these taxa shared three synapomorphies: (i) a line of pubescence on the anterolateral angle of the carapace, (ii) a reduced exog- nath on the outer maxilliped, and (iii) a characteristic form of the first sternite. Limited larval information for Parapinnixa suggested some resemblance to Sakaina (cf. Glassell 1933, Konishi 1981b), as supported by zoeal characters (Fig. 8). However, larval morphology indicated that Sakaina is not the sister group of the Dissodac- tylus complex.

In agreement with Griffith’s adult-based hypothesis, the two trees combining larval and adult characters (Fig. 2 7 A , B) suggested that the genus Clypeasterophilus and D ~ , - the Pacific species D . lockingtoni, D . nitidus and D .

each form a monophyletic group’ In disagreement with Griffith’s hypothesis, the first tree did not imply common exclusive ancestry for D . crinitichelis, D , mellitae and D . primitivus. However, the second tree suggested this common ancestry. The second tree has the same

Fig. 18.-A-D. Characters 6 and 7. Setation pattern on the mandible and relative development of the mandibular palp of megalopae within the Dissodactylus complex.-A. Clypeusterophilusstebbingi (from Mar- ques & Pohle in press u).--B. Dissodactylusprimitivus (from Pohle & Telford 1983).-C. C. rugutus (from Pohle 1984).-D. D. mellitue (from Marques & Pohle in press b). Scale bars = 0.1 mm.

relatives, with D . crinitichelis and D . primitivus forming their sister group. Dissodactylus lockingtoni represents the closest sister group of these four species, and D . mellitae is the sister group of these five species.

The adult phylogenetic analysis by Griffith (1987b) suggested that Clypeasterophilus and Dissodactylus (sensu stricto) are monophyletic groups (Fig. 26). This was corroborated in the present larval study (Fig. 26). However, there was some disagreement concerning the sister groups within Dissodactylus (sensu stricto). Griffith found that the Pacific species D . lockingtoni, D . nitidus, and D . xantusi formed a monophyletic group. The tree based on larvae suggested that D . lockingtoni does not share closest ancestry with the two other Pacific species.

topology as that based only on adult characters, when species without larval information were excluded from the latter. However, the first tree implied a new sister group relationship for the Dissodactylus complex which should be further examined with additional larval data from other species.

It is concluded that, even with limited larval information, there is evidence that this approach can shed further light on the evolution of pinnotherids in general and the Dissodactylus species complex in particular. Differences in setation were found to be particularly useful. Larvae of the remaining species need to be studied in order to fully evaluate the relative strength of larval evidence. However, results indicate that the combination of larval and adult information is better than either alone.

Fig. 19.-A-B. Character 8. Pattern of setation on the lower margin of the coxal endite of the maxillule of megalopae within the Dissodactylus complex.-A. Clypeasterophilus rugatus (absence of seta) (from Pohle 1984).--B. Dissodactylusprimitivus (presence of seta) (from Pohle & Telford 1983). Scale bars = 0.1 mm.



Table 111. States of I7 larval and 19 adult characters for eight species within the Dissodactylus complex (characters 18-36 from Grifjth 19876; see text and Figs 16-28 for character and character state definitions)

Larval characters Adult characters*

Species 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

Clypeasterophilus rugatus C. stebbingi Dissodactylus crinitichelis D. lockingtoni D. mellitae D. nitidus D. primitivus D. xantusi

1 0 0 0 1 0 2 0 0 0 0 1 0 0 0 0 1 0 1 1 0 0 0 1 1 1 2 0 0 I 0 0 1 0 0 0 1 0 0 0 1 0 0 1 0 0 1 1 0 0 0 0 1 0 1 1 0 0 0 0 0 1 2 0 0 I 0 0 1 0 0 0 0 1 1 1 1 1 1 1 1 0 1 0 1 0 1 1 0 1 0 0 1 1 1 0 0 0 0 1 1 0 0 0 0 0 0 0 0 1 1 1 3 0 3 1 1 1 1 0 2 0 0 1 0 1 0 0 1 1 0 0 I 0 1 0 1 0 1 1 0 1 1 1 0 1 1 1 0 1 3 1 0 1 1 0 3 0 0 0 0 1 0 0 1 1 1 0 0 0 0 1 1 0 0 0 0 0 0 0 0 1 1 1 2 1 3 1 1 0 0 0 2 1 1 1 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 0 1 I 1 0 1 1 1 1 0 1 1 1 1 1 0 1 0 1 1 0 1 0 0 1 1 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 1 1 3 0 3 1 1 1 0 0 2 1 1 1 0 1 0 0 1 1 0 1 0 0 0 0 1 0 0 0 0 1 1 1

*Griffith’s (1987b) characters 4 ,5 ,9 , 17,20-23 and 25 were excluded since they were uninformative for species with larval information

Y

A

I B

I

Fig. 20.-A-B. Character 9. Setation adjacent to the base of the scaphognathite within the megolopae of the Dissodactylus complex.-A. Dissodactylus mellitae (absence of the seta) (from Marques & Pohle in press b).-B. D. primitivus (prescncc of the scta) (from Pohle & Telford 1983). Scale bars = 0.1 mm.

10

Fig. 21.-A-C. Characters 10 and 11. Setation of the exopodite and epipodite of the first maxilliped for megalopac of the Dissodactylus complex.- A . Dissodactylus mellitae (from Marques & Pohle in press b).-B. Clypeasterophilus stebbingi (from Marques & Pohle in press a).-C. D. xantusi (from Pohle 1994). Scale bars = 0.1 mm.



I A

I B

I C

I-- D

I'

I

I

Fig 22 -A-D Characters 12 and 13 Shapc of the ischio-merus and relative development of dactyl of the third maxillipcd within the Dissodactylus complex -A Clypeasferophilus rugutus (from Pohle 1984) --B Drssodactylu prrrnztivuJ (from Pohle & Telford 1983) --C D nrtiduJ (from Pohle 1994) -D D mellitae (from Marques & Pohle in press b ) Scale bars = 0 1 mm

A I- I

O.lmrn B

Fig. 23.-A-B. Character 14. Setation on the merus of the last ambulatory leg within the megalopac of the Dissodactylus complex.-A. Dissodactylus lockingtoni (without aesthetasc-like seta) (from Pohle 1994).--B. D. nitidus (with aesthetasc-like seta) (from Pohlc 1989).



Y

A +I

B I------1

A +I

B

Fig. 24.-A-B. Characters 15 and 16. Serrate setae on dactyl and on propodus of the cheliped.-A. Clypeasterophilus rugatus (absent) (from Pohle & Telford 1984).-B. Dissodactylus crinitichelis (present) (from Pohle & Telford 1981b). Scale bars = 0.1 mm.

A

d c Fig. 25.-A-B. Character 17. Setation on the posterior border of the sternum.-A. Dissodactylus crinitichelis (absent) (from Pohle & Telford 1981b).-B. Clypeasterophilus rugatus (present) (from Pohle 1984). Scale bars = 0.1 mm.

C. stebbingi C. rugatus D. mellitae D. lockingtoni D. crinitichelis D. primitivus D . nitidus D . xantusi

\ \

2

Fig. 26. The most parsimonious cladogram summarizing sister group relationships among known larvae of the Dissodactylus complex using the data matrix of Table I11 (numbers indicate characters, and superscripts are the states for a given character).

Zoologica Scrip ta 24


C . stebbingi C . rugatus

A

f

C . stebbingi C . rugatus

\ ? D . crinitichelis D. xanturi D . nitidus D. lockinnioni D. primitivur D . mellitad

13’ 15 16 ’O yy- 1 4 27fs

7 ’

\

B

C

Lo 33 3

Fig. 27.-A-C. Thc two most parsimonious cladograms summarizing sister group relationships among the Dissodactylus species complex based on combined larval and adult characters (A,B) and Griffith (1987b) phylogenetic hypothesis based on adult morphology (C) (modified from Griffith 1987b) (numbers indicate characters, and superscripts are the states for a given character).



Acknowledgements

This work was supported through Research Grant A2313 (to G. Pohle) from the Natural Sciences and Engineering Research Council, Canada. The senior author is financially supported by a doctoral fellowship of the Conselho Nacional de Desenvolvimento Cientifico e Tecnol6gico (CNPq), of thc Brazilian Federal Government. We thank Drs Daniel Brooks and Malcolm Telford for reviewing the earlier drafts. Ernesto Campos of the Universidad Autonoma de Baja California provided larval specimens of four Pacific species. Also, we thank Dr Austin B. Williams from the U.S. National Museum, Smithsonian Institution, for providing one specimen of Pinnotheres politus.

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phylogenetic analysis of the pinnotheridae (crustacea, brachyura) based on larval morphology, with...

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