A NEW AMPHIPOD CRUSTACEAN, ORCIIESTOIDEABIOLLEYI, FROM COSTA RICA.
By TiioaiAs R. R. Stebbinc;.Of the Roi/al Soficfi/. London. EiujlaiiiJ.
Before proceeding to describe a new species of Talilrid;e I wish torefer tt) a former paper on Amphipoda from Costa Rica, in wliicli Ifigured and described as new Ilyaldla faxoni" pointing out its nearrelationsliip to other forms earlier described under various names.Recently, in lier very interesting paper cited below, Miss Weckel hasmade II. faxoni a synonym of the species which in her opinion oughtto be called II. Icnicherhochevi (Bate). The independence of //.faxoni is not a matter of great moment; but the question remains anopen one whether it may not be more inconvenient than necessary tofuse under one name the forms of IIy(dcUa which have been dis-tinguished as dentata and inerniis. Supposing that a single nameis reipiired, there are three to choose from Avith claims prior to liate'sknicTxerhocTxeri. These are the obscure AmpitJioe dentata Say, 1818,Amphitoc aztecus Saussure, 1858, and Anipliitlioe andina Philippi,1860. The reader inclined to accept a bias in a certain directionmay consult the notes on these names in the bibliography to the
"Challenger Amphipoda." 1888, as well as the references suppliedby Das Tierreich in 1000.In the Amphipoda of Das Tierreich there is an inconsistency be-tween pages 523 and 524, the former affirming that the [)alp of thefirst maxilla is one-jointed in the family Talitridie, the latter that itis two-jointed in the genus 2\ditru.s. The alternative character of
" minutel}^ two-jointed '' should have been added to the descriptionof the palp in the diagnosis of tlie family.Family TALITRID.E.1813-14. OrcJicstixUc Leacii. E(liiil)iir.!;b Encyclopicdia, VII, i). loli.1906. Talitridcv .Stebiung, Das Tierreicli, Lief. 21, p. 523.1907. OrcJiestiid(P Ada Weckel, Proe. U. S. Nat. Mus., XXXIII, p. 54.
" Pi-dc. U. S. Nat. Mns., XXVI, 1903. p. 92S, pi. lxi.Proceedings U. S National Museum, Vol. XXXIV? No. 1609.Proe. X. M. v.)l xxxiv?OS 111 241
242 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxiv.Genus ORCHESTOIDEA Nicolet.1849. Orche>it<n<lcn Nicolet, in Gay, Hist. Cliile, III, p. 229.1906. OrcJicstoulea Sterbing, Das Tierreicli, Lief. 21, p. .j27.This genus agrees with both sexes of I'alitrus and with the femaleof Talorchestia in having the first gnathopod simple, differing fromthe male of Talorchestia and both sexes of Orchestia in which the firstgnathopod is subchelate. All the four genera have the second gnatho-pod in the female feebly chelate, but in the male this is the caseonly with Talitrus, the second gnathopod of the male in the otherthree genera being powerfully developed. These distinctions do notenable us to separate a species of Talorchestia or O rchestoidea fromoue of Tah'tj-us. when only female, nor yet an Orchestia from aT(//orc/iesfi(u when only male sj)ecimens are available. But as theseanimals are generally plentiful, where they occur at all, any diffi-culty arising from the absence of one or other sex Avill not as a rulebe of long standing under the energy of modern research.ORCHESTOIDEA BIOLLEYI. new species.I'lalc XII.Integument smooth and shining, l)ut under a high power showingthe three-spiked markings often seen in this family. Fifth side-plateof pera'on as deep as fotu'th. Postero-lateral corners of third pleonsegment qiuidrate with minute projecting point.Eyes large, dark, roughly rounded, in the largest specimens sep-arated only by a short space at the top of the head.First antennae very short, third joint of peduncle rather the longest,e<iual to the little five-jointed fiagellum. Second antennjc in the malelonger than the body, last joint of peduncle considerably longer thanthe preceding joint, fiagellum ?)r)-jointed. more than thrice as long-as the peduncle ; in the female much shorter than the body, fiagellum23-jointed, not greatly longer than the peduncle.The mouth-organs are in close agreement with those of Talitrusand 7\ilorchestia. The minute i)alp of the first maxilla appears tobe 2-jointed, with the second joint considerably shorter than thefirst.The first gnathopods. in accord with the generic character, aresimple in both sexes, but in the male the rather large fifth joint hasat the distal end of the hind margin a transparent bulb or bubble-like expansion, wdiich is wanting in the female.The second gnathopods of the male have the fifth joint ver}^small and feebly separated from the strong ovoid sixth joint, thehind margin of which is characterized by having near the distal enda small transparent bulb, the distal end itself being rounded andtipped with a spine. Within this apex the strong finger closes into a
NO. 1609. A NEW AMPHIPOD CRUSTACEAN?STEBBINCl. 243pocket, being- fitted over a broad spinose curve of the pabii, betweenwhich and the hinge it inserts a squarish projection of its inner mar-gin into a corresponding depression of the pahn. The second gnatho-pod of the female is of tlie usual membranaceous character, the secondjoint expanded in the proximal half, the fifth joint wider and a littlelonger than the sixth, which is rather strongly and not narrowlyproduced beyond the diminutive longitudinal finger, which lies in asetulose gap of the sixth joint's front margin. In the male specimenfrom which the detail figures have been drawn one of the gnathopodsof the second pair is decidedly smaller than the other and is withoutthe transparent process on the hind margin. In another specimen,
Fig. 1.
?
Orche.stoide.\ biolleyi, male.probably abnormal, the apex. of the sixth joint of the second gnatho-pod is laterally outdrawn, obscuring its ordinary character. Onlyone member of the pair is present, and the specimen is otherwisedefective.The first three peraeopods are short, the second shorter than thefirst, with its finger more strongly notched. The third perseopod hasits second joint almost circular, much less in diameter than the lengthof the side-plate. The fourth and fifth perseopods are very muchlonger, the fifth having its second joint much wider than that of thefourth pair, and its total length somewhat greater. The fingers inthese two pairs are long and slender, in all the pairs there is anobliquely pointed spine in advance of the unguis. All the branchial
244 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. XXXIV.
vesicles are narrowh' twisted. The marsupial plates of the femaleexamined do not seem to be fully developed.The slender pleopods have along the peduncles two rows of shortspines and two coupling-hooks. The rami are about nine-jointed, andare scarcely as long as the peduncles.The first uropods have the peduncle longer than the subequal rami,one of which has conspicuous spines only at the apex. The secondpair have one ranuis nnich longer than the other, Avith the peduncle
I'll.;. '2.?Okciiewtoiiika I'.ioi.ley i , fkmall:.
of intermediate length. The third pair have the ranuis about ecjualin length to the ])eduncle. The telsou is about as broad as long,distally tapering, with a dividing line running up some part of thelength from the apex.Length of male about 10 mm., of female about 7.5 mm.Habitat.?Several specimens Avere collected in February, 1907, atPunta Arenas, Costa Rica (Pacific coast), in sand, under trunks oftrees, by the late Professor P. Biolley, out of respect to whom thespecific name has been given to this species.Type.?C'Ai. Xo. 38343, U.S.X.M.EXPLANATION OF PLATE NIL
/(. .s'. $ . II. s. 9- Lilies iiulicatinj: natural size of male and female si)eciniens,from which the details have been fisured.
'/. v.. a. i. Li)i)er and lower anteniue of male.//(..-. 1. First maxilla of male, the inner plate seen l>y transparence tliroiij,'lithe outer. The scale of magnification higher than in the other figures.git. L f/n. 2, gii. 1. 9, gii. 2, 9. First and second gnathopods of the male andfemale, with portions of the same more highly magnified.prp. 1, 2, 3, 4, .5. The five peraeopods, with parts of the first, second, and fifthmore highly magnified.urp. 1, 2, 3, T. The three uropods and the telson, with the latter more highlymagnified.Two uniform scales have been used for the lower and higher enlargementof all the parts except the first maxilla.
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. XXXIV PL. XII
A New Amphipod Crustacean.For explanation of plate see page 244.