16 April 1996 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 109(l):7a-74. 1996 A new of the axiid shrimp Acanthaxius from the Caribbean (Crustacea: : Thalassinidea)

Brian Kensley Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, U.S.A.

Abstract.—Acanthaxius kirkmilleri is described from slope depths (420^40 m) in the Caribbean Sea off Anguilla, and is the first unambiguous record of the genus in the Atlantic. The species is characterized by a slender rostrum longer than the eyestalks, highly spinose and relatively slender chelipeds of pereopod 1, and seven spines on the suture of the lateral uropodal ramus.

A single female specimen of a distinctive per) margin of propodal palm and dactylus. axiid shrimp was collected by the R/V John See Table I for branchial formula. Pleopo- Elliott Pillsbury in 1969, off Anguilla. The dal rami slender; pleopod 1 in female uni- specimen is described here, as part of a se­ ramous; pleopods 2-5 with appendix inter­ ries of papers documenting the diversity of na. Lateral uropodal ramus with transverse the in the western Atlantic, and is suture. Telson longer than wide, with dorsal deposited in the collections of the National submedian fixed spines (Table 1). Museum of Natural History, Smithsonian Remarks.—The definition of this genus Institution, Washington, D.C. (USNM). contains some uncertainties, as the type species, A. pilocheira Sakai, 1987, is Family Axiidae known only from the holotypic female. Im­ Genus Acanthaxius portant characters of pleopods 1 and 2 of Sakai & de Saint Laurent, 1989 the male are is thus unknown, although the absence of pleopod 1 was deduced from Acanthaxius Sakai & de Saint Laurent, other species placed in the genus. Three of 1989:4, 12, 14, 66.—Poore, 1994:98 the species assigned to this genus by Sakai [key].—Sakai, 1994:192. & de Saint Laurent (1989) and Sakai Type species.—By original designation, (1994), A. caespitosa (Squires, 1979), A. Axiopsis {Axiopsis) pilocheira Sakai, 1987. hirsutimana (Boesch & Smalley, 1972), and Type locality: off Honshu Island, Japan, A. spinosissimus (Rathbun, 1906), do not fit 360 m. Gender: Masculine. the generic definition, in that all three have Diagnosis.—Gonochoristic. Rostrum at pleopod 1 of the male present, and the car­ same level as anterior carapace, narrow, lat­ apace is covered with granules, both fea­ eral margins dentate; carapace glabrous to tures more characteristic of Oxyrhynchaxius faintly rugose; with median, submedian and Parisi, 1917. The species A. spinulicauda lateral carinae dentate; post-cervical carina (Rathbun, 1902), also included in Acan­ absent. Eye with cornea pigmented; eye- thaxius Sakai & de Saint Laurent, 1989, is stalk relatively elongate. Antennal scapho- clearly a species of Calocarides Wollebaek, cerite (acicle) just reaching distal margin of 1908. The use of the post-cervical carina, peduncle article 4, slightly arcuate. Maxil- present in some species, absent in others, liped 3, exopod not clearly bent; ischial also needs reassessment as a diagnostic crest well developed. Pereopod 1, chelipeds character. asymmetrical, with spines on anterior (up­ The advanced characters of the genus VOLUME 109, NUMBER 1 71

Table 1.—Branchial formula for Acanthaxius pil- rostrum slender, with 2 pairs of strong dor­ ocheira. r = reduced. sal teeth (apex missing); median carina

Maxillipcds Pcreopods starting at rostral base, with 2 teeth anterior I to tubercle, 1 posterior; submedian carina with 4 teeth; lateral carina with single Exopod 1 1 I ^ _ _ _ _ strong tooth posterior to basal rostral tooth; Epipod 111 1111 — postcervical carina poorly defined, most Podobranch — rr rrr — — Arthrobranch -—2 2222 — marked anteriorly. Abdominal pleuron 1 Pleurobranch ventrally narrowed; pleuron 2 broad, ven- Setobranch - — 1 11111 trally truncate; pleura 3-5 with tiny denticle on anterior margin, anteroventrally round­ ed, posteroventrally slightly angled. Telson with lateral margin having single anterior would appear to be the relatively slender tooth, 2 mobile posterolateral spines, pos­ and dentate rostrum, with its basal pair of terior margin convex, with median tooth; spines in a supraorbital position; the form dorsal surface with 2 pairs of teeth (poster- of the chelipeds of pereopod 1, and es­ iormost tooth on right side doubled). pecially that of the smaller chela with the slender dentate fingers being 1.5-2.0 times Antennal scaphocerite (acicle) slender, longer than the propodal palm; the presence acute, reaching to distal margin of peduncle of spines on the upper margins of the dac- article 4. Maxilliped 3, ischium with 3 teeth tylus and propodus of pereopod 1 chelae; on posterior margin; merus with 5 teeth in­ the absence of pleurobranchs; and the pres­ creasing in length distally on posterior mar­ ence of epipods on pereopods 1 -A. gin. Pereopod 1, larger chela, ischium with Species: 4 teeth on posterior margin; merus with 7 Acanthaxius amakusana (Miyake & Sakai, teeth and several smaller denticles on pos­ terior margin, 5 strong distal teeth on an­ 1967). Amakusa Island, Kyushu, Japan, terior margin; carpus with 3 strong teeth on 20-40 m. anterior margin, several smaller denticles Acanthaxius kirkmilleri. new species. Off on lateral surface, including strong submar- Anguilla, 421^39 m. ginal tooth; fingers subequal in length to Acanthaxius miyazakiensis (Yokoya, 1933). propodal palm, propodus strongly setose on Southern Miyazaki-ken, Japan, 137 m; upper and lower surfaces, with 4 strong Philippines, 136-210 m. teeth on anterior margin, row of 12 sub- Acanthaxius pilocheira (Sakai, 1987). Off marginal teeth on ventrolateral surface, lat­ Honshu Island, Japan, 360 m. eral surface of palm with many small acute Acanthaxius polyacantha (Miyake & Sakai, denticles; fixed finger with cutting edge 1967). East China Sea, 118 m. bearing numerous small rounded teeth; dac- Acanthaxius polychaetes Sakai, 1994. Off tylus bearing 5 strong teeth on upper mar­ Great Barrier Reef, Australia, 260 m. gin, cutting edge bearing numerous small rounded teeth. Smaller chela, ischium, me­ Acanthaxius kirkmilleri, rus, and carpus as in larger chela; fingers new species about Vi longer than propodal palm, latter Figs. 1, 2 setose, with 4 strong teeth on upper margin, row of about 10 submarginal teeth ventral­ Material examined.—Holotype, USNM ly, lateral surface with several small acute 243492, 9 carapace length 12.0 mm, R/V, denticles, fixed finger with cutting edge John Elliott Pillsbury sta P-984, off An­ straight, bearing numerous small serrations; guilla, 18°26.4'N, 63°12.6'W, 421-439 m, dactyl bearing 4 strong teeth on upper mar­ brown mud bottom, 22 Jul 1969. gin, cutting edge straight, bearing numerous Diagnosis.—Female: Carapace glabrous; 72 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

Fig. 1. Acanthaxiiis kirkmilleri. new .species, hoiotype (USNM 243492). A, Carapace in lateral view; B, Anterior carapace in dorsal view; C, abdomen in lateral view; D, telson and riglit uropod in dorsal view. Scale = 2 mm. small serrations. Pereopod 2, anterior and Pereopod 5, propodus with distolateral clus­ posterior margins of all articles setose; is­ ter of setae; dactylus setose. Pleopod 1 a chium with single strong posterodistal single slender ramus, distally flagelliform. tooth; merus with 3 strong teeth on poste­ Pleopods 2-5 with slender appendix interna rior margin; carpus with single strong tooth articulating at about proximal third of en- at midlength of anterior margin, Pereopod dopod. Uropod with lateral ramus having 2 3, merus with 3 teeth on posterior margin; teeth on lateral margin, mobile spine at an­ propodus with 5 small clumps of short gle of suture, 6 spines along suture; mesial spines on posterior margin. Pereopod 4, ramus with 2 teeth on lateral margin, 4 teeth merus with single small posterodistal tooth; on dorsal ridge including distal marginal dactylus setose; propodus with 4 small tooth. clumps of tiny spines on posterior margin. Remarks.—The major differences be- VOLUME 109, NUMBER 1 73

Fig. 2. Acanthaxius kirkmilleri. new species, holotype (USNM 243492). A, Pereopod I, larger cheliped; B, Pereopod 1, smaller cheliped; C, Pereopod 2; D, Pereopod 3; E, Pereopod 4; F, Pereopod 5; G, Pleopod I; H, Pleopod 2. Scale (A-F) = 2 mm tween this western Atlantic species and the The differences between the present spe­ holotype of A. pilocheira (USNM 231418) cies and the other Japanese congeners are lie in the lateral ramus of the uropod (lateral easily discerned: A. miyazakiensis is a far margin more spinose than A. kirkmilleh), more setose species, especially on the che­ the generally more spinose and slightly lipeds and carapace; A. polyacantha pos­ more robust chelipeds of pereopod 1 in A. sesses a markedly tuberculate carapace, and pilocheira, and the more elongate telson relatively more robust chelipeds; A. amak- (1.5 times longer than basal width) in A. usana has a rostrum shorter than the eye- kirkmilleri (1.25 times longer tnan basal stalks, and a relatively broader telson. The width in A. pilocheira). Australian species A. polychaetes is more 74 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

setose, especially on the carapace and ab­ ica.—Proceedings of the United States National domen, and possesses squatter and more se­ Mu.seum 24( 1272):885-905. tose chelipeds of pereopod I . 1906. The Brachyura and Macrura of the Ha­ waiian Islands.—U.S. Fish Commission Bulle­ Etymology.—The species is named for tin for 1903, Part 3:827-930. Dr. Kirk D. Miller, longtime friend and Sakai, K. 1987. Two new Thalassinidea (Crustacea: companion. Decapoda) from Japan, with the biogeograph- ical distribution of the Japanese Thalassinid­ ea.—Bulletin of Marine Science 41(2):296-308. Acknowledgments . 1994. Eleven species of Australian Axiidae I am grateful to Dr. Rafael Lemaitre for (Crustacea: Decapoda: Thalassinidea) with de­ reading the manuscript, and making useful scriptions of one new genus and five new spe­ cies.—The Beagle, Records of the Museums suggestions for its improvement. and Art Galleries of the Northern Territory 11: 175-202. Literature Cited , & M. de Saint Laurent. 1989. A check list of Axiidae (Decapoda, Crustacea, Thalassinid­ Boesch, D. F, & A. E. Smalley. 1972. A new axiid ea, Anomura), with remarks and in addition de­ (Decapoda, Thalassinidea) from the northern scriptions of one new subfamily, eleven new Gulf of Mexico and tropical Atlantic,—Bulletin genera and two new species.—Naturalists 3:1- of Marine Science 22(l):45-52. 104. Miyake, S., & K. Sakai. 1967. Two new species of Squires, H. J. 1979. Axiopsis caespitosa (Thalassinid­ Axiidae (Thalassinidea, Crustacea) from the ea, Axiidae), a new species from the Pacific East China Sea.—Journal of the Faculty of Ag­ coast of Colombia.—Canadian Journal of Zo­ riculture, Kyushu University 14(2):.303-310. ology 57(8): 1584-1591. Parisi, B. 1917. I Decapodi giapponesi del Museo di Wollebaek, A. 1908. Remarks on decapod Milano. V. Galatheidea e Reptantia.—Atti della of the North Atlantic and the Norwegian Fiords Societa Italiana di Scienze Naturali 56:1-24. (I & II).—Bergens Museums Aarbog 12:1-74. Poore, G. C. B. 1994. A phyiogeny of the families of Yokoya, Y. 1933. On the distribution of decapod crus­ Thalassinidea (Crustacea: Decapoda) with keys taceans inhabiting the continental shelf around to the families and genera.—Memoirs of the Japan, chiefly based upon the materials collect­ Museum of Victoria 54:79-120. ed by S. S. Soyo-Maru, during the year 1923- Rathbun, M. J. 1902. Descriptions of new decapod 1930.—Journal of the College of Agriculture, crustaceans from the west coast of North Amer­ Tokyo Imperial University 12(1): 1-226.