Records of Rare Hawaiian Decap?d Crustacea

ROBERT W. HIA.TT1

WITHIN THE PAST YEAR four crustaceans whichare rare or previously unknown in Hawaii havebeen collected. Since these records are of im­portance to both taxonomists and students ofanimal distribution, it has been deemed worthwhile to make them available. The specimensare deposited in the collection of the Universityof Hawaii Marine Laboratory.

Suborder NATANTIA

Family RHYNCHOCINETIDAE

Rhynchocinetes rigens GordonKnown previously only from the island of

Madeira (Gordon, 1936: 76) and from Ber­muda (Burkenroad, 1939: 310; Gurney andLebour, 1941: 113), this shrimp is found on andjust off the reef on the south shore of the islandof Oahu, Hawaiian Islands. This species, theonly one of the six recognized members of thegenus known to occur in the Atlantic, has notbeen found in the Pacific previously. Since ithas been found in Hawaii , which is the easternlimit of the most widely distributed Indo­Pacific species, it is reasonable to suppose thatit occurs in many other Pacific regions west ofHawaii, but thus far it has not been recorded.Perhaps the late discovery of this species in anarea in which so much collecting has been donemay be attributed to the fact that here, as inBermuda, this species occurs as a sedentary, noc­turnal, littoral form and thus would not be eas­ily collected unless suitable collecting gear wereused. The smallest Hawaiian specimens weretaken with the aid of a light and a dip net; thelarger ones were taken from a fine-meshed fish

1 Department of Zoology and Entomology, Univer­sity of Hawaii. Manuscript received July 3, 1947.

trap set in approximately 6 fathoms off Dia­mond Head, Oahu. One female specimen col­lected on February 19, 1947, was ovigerous.

Hawaiian specimens ranged in length from55 to 115 millimeters compared to a range offrom 80 to 97 millimeters for the specimensfrom Madeira.

The vertical striae on the carapace are welldeveloped in both sexes but are most conspicu­ous in the males. The third tooth behind thearticulation of the rostrum is largest in all theHawaiian specimens, as it is in the holorype,All Hawaiian specimens have 9 ventral teethon the rostrum, whereas the holotype has 8. Nosignificance may be attached to this feature,however, because the ventral teeth on the rostraof the paratypes vary from 7 to 11. The dorsalteeth of the rostrum are arranged similarly to

those of the holotype. In the Hawaiian femalesthe articulation of the rostrum extends less thanhalf way to the strong lateral ridge, whereas inthe holotype it extends almost to the ridge. Inmales from both localities the articulation ex­tends to the ridge.

No significant differences were noted betweenthe appendages of the holotype and those of theHawaiian specimens except in the first pleopodof the females. The Hawaiian specimens havea broad, scale-like protuberance extending fromthe disto-Iateral area of the protopodite as faras the basal one-fourth of the exopod. The lat­eral and distal margins of this protuberance arethickly clothed with setae.

The branchial formula of Hawaiian speci­mens is identical with that of the Madeiranspecimens, which differs from the branchialformula of R. t'YPus M.-Edw. in that the arthro­branch corresponding to the fourth pereiopod

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Decapod Crustacea-HIATT

(on XIII. ) is absent. The total number ofarthro- and pleurobranchs on IX. to XIV. isthus 10 instead of 11. Well-developed epi­podites occur on all the pereiopods with the ex­ception of XIV.

Rhynchocinetes rugulosus Stimpson

Although this species is known from theHawaiian archipelago through a small specimendredged up in 1902 (Rathbun, 1906:911) bythe "Albatross" at French Frigate Shoals in 17fathoms, and another small specimen taken atLaysan Island in 1923 (Edmondson, 1925:6),a specimen taken off Oahu is the first instanceof its occurrence among the main HawaiianIslands. The species is apparently widespreadthroughout the Indo-Pacific region, havingbeen first known from Port Jackson, Australia(Stimpson, 1860:36). Later it was collected atLord Howe Island (McCulloch, 1909:310), theKermadec Islands (Chilton, 1910:548) , theLoyalty Islands (Borradaile, 1916:85), and inJapan (Kemp, 1925:263; Kubo, 1936:1887).

One male specimen 80 millimeters in lengthwas taken in a small-meshed fish trap off Dia­mond Head, Oahu, along with two large malesof R. rigens. This specimen is considerablylarger than Stimpson's type; it has 5 teeth dor- ·sally near the tip of the rostrum as comparedto 3 for the type specimen, and it has 13 teethbelow as compared to 12 in the type. Thesedifferences are probably within the range ofvariation for these variable structures. In othermorphological aspects no differences from thetype are apparent .

Two of the six species comprising the un­usual genus ·R h'Ynchocinetcs, in which the ros­trum is articulated with the carapace, are nowknown to occur in Hawaii. They may be dis­tinguished as follows:

1. Two teeth on carapace behind rostralarticulation; no tooth on either side offourth or fifth abdominal somites aboveposterior edge of pleuron; rostrum with­out lateral ridge, articulation with cara­pace complete. . .. R. rugulosus Stimpson.

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2. Three teeth on carapace behind rostralarticulation ; a tooth on each side of fourthand fifth abdominal somites above pos­terior edge of pleuron; rostrum withstrong lateral ridge, articulation with cara­pace incomplete. . . . R. rigens Gordon.

Family GNATHOPHYLLIDAE

Hymenocera elegans Heller

A female specimen measuring 55 millimetersin length was taken at a depth of 4 fathoms ina crevice in lava rock encrusted with coral(Porites lobata) , located about 200 feet towardKohala from the new dock at Kawaihae on theisland of Hawaii. This record represents thesecond in Hawaiian waters for this bizarreshrimp, and the first record for the island ofHawaii. Edmondson (1935: 17) collected thefirst Hawaiian representative in 1934 amongthe branches of a Porites sp. coral head on ashallow reef in Kaneohe Bay, Oahu. The colorpattern of the present specimen was almostidentical with the one described by Edmondson.

Suborder REPTANTIAFamily LATREILLIDAE

Latreillopsis hawaiiensis Edmondson

This species, described by Edmondson (1932:2) from a sirigle specimen, has been col­lected in Hawaii for the second time. On Janu­ary 28, 1947, one of these giant, deep-sea crabsbecame entangled in the fish lines of a fishermanwho was bottom-fishing to a depth of 500fathoms, 5 miles directly off Kewalo Basin,Oahu, and it was subsequently brought to myattention. Since the type specimen was takenat 30 fathoms and the present specimen wascollected at 500 fathoms, it is apparent that thebathymetric range of this unusual crab is great.

The greatest length of this male specimen is126 mm.; the greatest width is 111 mm., almostidentical with the type specimen in size. Therostral spine and the supraocular spines are worn

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down greatly. Other morphological featurescheck with the original description.

Two species of lepadid barnacles thickly. clothe certain parts of the exoskeleton. Thebarnacles are grouped closely in the exhalantbranchial grooves and on the mouth parts.Many others are attached to the pereiopods andto the carapace and abdomen. These same bar­nacles occur on the type specimen, but are muchless abundant.

Two pereiopods, the right third and fifth,are severed at the fracture plane and the frac­tured surface contains only the darkened dia­phragm which indicates that the appendageswere probably lost during the ascent of theanimal to the surface. The remaining legs showno signs of recent regeneration. Round punc­tures at which the exoskeleton has been brokenthrough are present on the merus of the rightcheliped, on the carpus of the left cheliped, onthe merus of the left fourth pereiopod, and onthe merus of the right second pereiopod. Sim­ilar punctures were present on the type speci­men.

REFERENCES

BORRADAILE, 1. A. 1916. British Antarctic( trTerra Nooa") Expedition, 1910. Zoology3: 75-110, 16 fig. Nat. Hist. Rpt. Brit. Ant­arctic Exped. 1910.

BURKENROAD, MARTIN D. 1939. Some re­marks upon non-peneid Crustacea Decapoda.Ann. Mag. Nat. Hist. XI, 3: 310-318.

CHILTON, CHARLES. 1910. The Crustacea ofthe Kermadec Islands. New Zeal. lnst., Trans.43: 544-573, 4 fig.

PACIFIC SCIENCE, Vol. II, April, 1948

EDMONDSON, C H ARLES H. 1925. Marinezoology of tropical central Pacific. BerniceP. Bishop Mus., BuI. 27: ii+148, 11 fig., 11pI.

---- 1932. A giant Latreillopsis from Ha­waii. Bernice P. Bishop Mus., Occas. Papers9(24): 1-9,1 fig., 1 pI.

1935. New and rare PolynesianCrustacea. Bernice P. Bishop Mus., Occas.Papers 10(24): 1-40,11 fig., 2 pI.

GORDON, ISABELLA. 1936. On the macrurangenus Rbyncbocinetes, with description of anew species. Zool. Soc. London, Proc. 1936:75-88, 7 fig.

GURNEY, ROBERT, and MARIE V. LEBOUR.1941. On the larvae of certain CrustaceaMacrura, mainly from Bermuda. Linn. Soc.London, Jour. 41 (277) : 89-181, 26 fig.

KEMP, STANLEY. 1925. Notes on CrustaceaDecapoda in the Indian Museum. IndianMus., Rec. 27 (4): 249-343, 24 fig.

KUBO, I. 1936. On a Japanese shrimp of genusRhynchocinetes, R. rugulosus Stimpson. Bot.and Zool., 4: 1887-1892, 2 fig.

MCCULLOCH, ALLAN R. 1909. Studies in Aus­tralian Crustacea. No.2. Austral. Mtts., Rec.7: 305-314,2 fig.

RATHBUN, MARY J. 1906. The Brachyura andMacrura of the Hawaiian Islands. U. S. FishComm. Bul. 1903: 827-930, 79 fig., 24 pI.

STIMPSON, W. 1860. Prodromus descriptionisanimalium evertebratorum, quae in Expedi­tione ad Oceanum PacificumSeptentrionalem,a Republica Federata missa, CadwaladaroRinggold et Johanne Rodgers Ducibus, ob­servavit et descripsit. A cad. Nat. Sci. Phila.,Proc. 1860: 22-47.