the beetle genus lara by p. darlington, · 2019. 8. 1. · 1929] on the dryopid beetle genus lara...

328 Psyche [December

ON THE DRYOPID BEETLE GENUS LARA

BY P. J. DARLINGTON, JR.

Collecting at North Bend, Washington, in July, 1927,yielded a large series of the dryopid genus Lara, which wasdescribed in 1852 by Leconte (Proc. Acad. N. S. Philadel-phia 5, 1852, p. 42.) to co.ntain a single species from Cali-fornia. Superficial examination showed at once that therewere two species represented in the Washington material.Comparison with the type of L. avara Lec. proved furtherthat the insect I had at first identified as that species wasat least subspecifically distinct, so that it is now possibleto discriminate two. new forms and at the same time togive a brief account of their habits.

In our fauna Lara is an isolated genus of the Potamo-philini, seeming to be, as Lecont.e says in the original de-scription, "the desired link connecting the anomalous Eury-palpus (Psephenus) with the true Parnidm. There areseveral apparent relatives, such as Disersus, in Central andSouth America, however. Leconte’s description of Lara issufficiently full, and the genus has been figured by Hornin the Trans. American Ent. Soc., 10, 1882, Plate 6, fig. 16.

Key to the Species of Lara

Pronotum with the hind angles acute, but scarcely moreprominent than the middle lobes; elytral pubescence uni-form L. gehringiPronotum with the. hind angles acute and prominent;

alternate elytral intervals with the pubescence less decum-bent, so that the elytra appear dark with sericeous lines.

Size larger; elytra wider as compared with the pro-thorax; prono,tum proportionately longer, narrower,and with more prominent front and hind angles.

L. avara amplipennisCharacters opposed to those above L. avara avara

1929] On the Dryopid Beetle Genus Lara 329

Lara gehringi sp. nov.

Text figure "a".Black throughout. Punctuation and pubescence above

and below almost as in Lara avara, except that there is noalternation of pubescence on the elytral intervals. Gen-eral form similar to hat of L. avara, but the pronotumless strongly convolved and its side margins less stronglysinuate throughout. Hind pronotal angles only moderatelyprominent, scarcely more so than the sides of the pro.notumat middle. Genitalia of 3 definitely more decurved apicallythan in L. avara.

Length to apex of elytra 5.7--6.5 mm.

The 3 holotype and one paratype are from NORTHBEND, WASHINGTON, July 28, 1927. One 3 paratype is

Fig. 1. Outlines of pro.notum and elytra of a, La.ra gehringi;b, Lara avara avara; e, Lara avara amplipennis. All are magni-fied about 6.5 diameters.

from BARTLETT SPRINGS, CALIFORNIA, collected by A.Fenyes. The holotype is in my own collection, the NorthBend para.type in the collection of Dr. J. G. Gehring, and

330 Psyche [December

the Californian paratype is returned to Mr. H. C. Fall, whovery kindly loaned the specimen to me for the presentstudy.

The important diagnostic characters of Lara gehringiare set forth in the key. The Californian specimen differsfrom the other two in being a little more shining above.

I take great pleasure in naming this species for Dr. JohnGeorge Gehring, who was almost my first entomologicalcorrespondent, and to whom I owe my western trip of thesummer of 1927.

Lara avara amplipennis subsp., nov.

Text figure "c".

Generally similar in form and sculpture, as well as gen-italia, to typical Lara avara, but larger, with the elytra alittle wider as compared with the prothorax. The pro-notum is proportionately a little longer and narrower, withboth the anterior and posterior angles more prominent.These differences taken together give the insect a recog-nizably modified appearance, although they do not impressone as being o.f specific value. There seem to be no externaldifferences between the sexes.

Length to apex of elytra (amplipennis) 7.3--8.1 mm.(avara) 6.87.2 mm.

Length of an elytro.n (amplipennis) 6.1--6.5 mm.(avara) 5.2--5.4 mm.

Since the total length depends partly on the insect’sposition at death, the. measurements of elytral length showthe comparative size of the two subspecies more accurately.

Holotype 3 fro.m NORTH BEND, WASHINGTON, July 28,1927, in my collection. Paratypes" 49 3 3 from thetype locality, July 27-31; 2 3 from REVELSTOKE, BRITISHCOLUMBIA, August 14, 1927. Paratypes in the Museum o.fComparative ZoSlogy, the United States National Museum,the Californi.a Academy of Sciences, the Canadian National

1929] On the Dryopid Beetle Genus Lara 331

Collection, and the private collections of Mr. H. C. Fall,Dr. J. G. Gehring, and the writer.

This series of amplipennis has been compared with thetype and one other California.n specimen of true Lara avarai- the Leconte Collection in the Museum oi ComparativeZoSlogy at Cambridge. For the privilege o2 making thiscomparison I am indebted to the authorities o2 the museum,and particularly to Professor Nathan Banks, Curator ofInsects.Horn speaks oi ha.ving seen a specimen of Lara avara

on a log under water in a swift stream. I 2ound the genusonly on log jams in large streams which were both swiftand cold. The insects behave much like Psephenus, butare, perhaps, less alert, or they are usually 2ound on thelower sides o projecting stubs or in crevices, just at waterlevel. They are among the most resourceful o2 beetles inthe presence oi danger, 2or they can choose between craw-ling down a log into deep water, flying, or dropping intothe current, which whirls them swiftly away. The ma-jority ride the current or a yard or two and then takewing. I owe my fine series of the genus almost entirelyto a systematic but temporarily unsuccessful sea.rch orAmphizoa striata Van Dyke, of which North Bend is thetype locality.

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the beetle genus lara by p. darlington, · 2019. 8. 1. · 1929] on the dryopid beetle genus lara...

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