A new genus and species, Dumosus atari of the Maera group from coral rubble at Belize is described. It is related to Gammarella and is probably cryptic. The eyes are reduced. Dumosus differs from Gammarella in the loss of medial setation on the maxillae, reduction of article 3 on the mandibular palp, loss of article 2 on the outer ramus ofuropod 3, and in the loss of major spination on the plates of maxilla I and the maxilliped; in contrast to Gammarella, Dumosus retains the plesiomorphic uropod 3 typical of the Maera-group

Barnard, J. L.

Thomas, James Darwin

NSU Works

Nova Southeastern UniversityNSUWorksOceanography Faculty Articles Department of Marine and Environmental Sciences1-1-1985A New Marine Genus of the Maera Group(Crustacea: Amphipoda) from BelizeJames Darwin ThomasNewfound Harbor Marine Institute, thomasjd@nova.eduJ. L. BarnardSmithsonian InstitutionFind out more information about Nova Southeastern University and the Oceanographic Center.Follow this and additional works at: http://nsuworks.nova.edu/occ_facarticlesPart of the Marine Biology Commons, and the Oceanography and Atmospheric Sciences andMeteorology CommonsThis Article is brought to you for free and open access by the Department of Marine and Environmental Sciences at NSUWorks. It has been acceptedfor inclusion in Oceanography Faculty Articles by an authorized administrator of NSUWorks. For more information, please contactnsuworks@nova.edu.NSUWorks CitationJames Darwin Thomas and J. L. Barnard. 1985. A New Marine Genus of the Maera Group (Crustacea: Amphipoda) from Belize.Proceedings of the Biological Society of Washington , (3) : 630 -635. http://nsuworks.nova.edu/occ_facarticles/605.PROC. BIOL. soc. WASH. 98(3), 1985, pp. 63()...635 A NEW MARINE GENUS OF THE MAERA GROUP (CRUSTACEA: AMPHIPODA) FROM BELIZE James Darwin Thomas and J. L. Barnard Abstract. -A new genus and species, Dumosus atari of the Maera group from coral rubble at Belize is described. It is related to Gammarella and is probably cryptic. The eyes are reduced. Dumosus differs from Gammarella in the loss of medial setation on the maxillae, reduction of article 3 on the mandibular palp, loss of article 2 on the outer ramus ofuropod 3, and in the loss of major spination on the plates of maxilla I and the maxilliped; in contrast to Gammarella, Dumosus retains the plesiomorphic uropod 3 typical of the Maera-group. Legend for Figures Capital letters in illustrations are explained in the following list; lower case letters to the right of capital letters or in the body of an illustration are explained also in the following list; lower case letters to the left of capital letters are provided for subsidiary figures to note illustrated specimens listed in "Material." For each page of figures one main specimen is called " unattributed" and lacks letter des-ignation. B, body; C, coxa; D, dactyl; G , gnathopod; I, inner plate; L, labium; M , mandible; 0, outer plate or ramus; P, pereopod; R, uropod ; S, maxilliped; T, tel son; U, labium; Y, palp; W, pleon; X, maxilla; Y, gill; 0 , opposite; r, right. Dumosus, new genus Diagnosis. -Head and antennae of Elasmopus-form, thus rostrum small, an-teroventral antennal sinus small but notch absent, antenna 1 of medium length, article 2 nearly as long as 1, article 3 much shorter, accessory flagellum 3-articulate; antenna 2 very short, slightly exceeding article 2 of antenna I , flagellum very short, not longer than article 5 of peduncle, 4-articulate. Prebuccal mass weakJy extended anteriorly, upper lip rounded below. Mandib-ular incisors toothed, laciniae mobiles and rakers present on both sides, molar triturative, with large seta on right , small seta on left , palp article I scarcely elongate, article 2 naked, article 3 about 70 percent as long as 2, slender, linear, with I D-seta, 2 E-setae. Lower lip with fleshy inner lobes and well developed mandibular lobes. Inner plate of maxilla I with I apical, I subapical medial seta, outer plate with 7 spines, palp article I elongate, armament of right and left palps asymmetrical. Plates of maxilla 2 slender, inner with one medial seta. Inner plate of maxilliped lacking thick spines, bearing only setae, outer plate with medial and apical spines, palp poorly setose, article 3 with apical hook, dactyl stubby, with medi urn nail. Coxae of ordinary length, poorly selose, coxa I quadrate, unproduced anteriorly, coxae 1-2 with posteroventral tooth-notch, coxa 3 slightly the narrowest of coxae 1-4, posterodorsal excavation shallow, coxa 5 much shorter than 4, lobes of coxae 5-6 shallow. Simple gills on coxae 2-6; female unknown. VOLUME 98, NUMBER 3 631 Gnathopod I small, of melitid form, carpus and pro pod us subequally long, carpus not lobed, propodus with stiff posterior setal-spines, palm oblique, weakly sculptured. Male gnathopod 2 greatly enlarged, metacarpus with posterodistal sharp tooth (thus almost metacarpochelate), carpus short, strongly lobate, hand large, pyriform, palm and hind margin continuous, palm undefined, armed with few spines and many long apically curved bulbar setae, dactyl much shorter than false palm. Pereopods 3-4 ordinary, slender, pair of locking spines asymmetrical , dactyl with 2 main inner setules near base of nail, no outer tooth. Pereopods 5-7 of short form but increasingly elongate from 5 to 7, of reverted form, article 2 on pereopods 5-6 of narrow pyriform shape with weak posterior sinuosity, postero-ventrally lobate, posterior serrations weak to moderate respectively, remaining articles slender; pereopod 7 with shield-like article 2 bearing medium castellations posteriorly. Pleopods well developed, peduncle long, rami equally long. Pleon unarmed dorsally. Epimera diverse, third dominant, epimeron I with subventral ridge, naked ventrally, with small posteroventral tooth, epimeron 2 with lateral ridge, one facial spine, large posteroventral tooth; epimeron 3 nearly straight behind, with medium tooth and posteroventral serrations below main tooth, I facial spine. Uropod I with strong basofacial spine, strong apicolateral spine; uropods 1-2 with long apical spines, outer ramus of uropod I lacking marginal spines, other rami with few marginal spines. Uropod 3 small, aequiramolls, not exceeding uropods 1-2, peduncle short, rami lanceolate, sharp, inner only with tiny apical armament, outer similar apically also with 2 sets of lateral armaments. Telson short but longer than broad, deeply cleft, each apex bifid, with one spine and setule, each lobe with subapical lateral setule set. Type-species. -Dumosus atari, new species. Etymology. - Dumosus from "covered with thorn bushes" referring to gnatho-pod 2, and atari, a Carib Indian word for star. Relationship. - The present genus differs from Maera in the Elasmopus-like male gnathopod 2 lacking defined palm. As far as we know, no species of Maera has a shield-like article 2 on pereopod 7, nor the degree of diversity of pereopods seen in this species. This genus differs from Elasmopus in the linear article 3 of the mandibular palp, with lanceolate and poorly armed rami of uropod 3. It bears close resem-blance to Lupimaera Barnard and Karaman (1982) (based on Maera lupana J. L. Banard, 1969) but the rami of uropod 3 are slender and poorly armed, coxa 5 is short, and article 2 of pereopods 5-7 is diverse, unlike Lupimaera. Unlike Meximaera Barnard (1969), the new genus has enlarged and non-female-like gnathopod 2, poorly armed rami ofuropod 3, poorly armed mandibular palp, and diverse pereopods 5-7. A superficial resemblance occurs between this genus and the Caribbean cave genus Paraweckelia Shoemaker (1959). Although Paraweckelia appears less spe-cialized in the presence of more medial maxillary setae, non-diverse perea pods 5-7 , long and spiny rami ofuropod 3, and longer antennae, Paraweckelia is more specialized in the apomorphic telson. Because of the poorly developed rami of uropod 3 and diverse pereopods 5-7 , Dumosus cannot be ancestral to hadziids and weckeliids. 632 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON MI B Mr VXfo u L S1 VXl Xl X2 S Fig. 1. Dumosus alari, new species, holotype, male "x." VOLUME 98, NUMBER 3 Gf D4 G2 P4 y y Cf C2 C3 Fig. 2. Dumosus atari, new species, ho!otype, male "x," sv MI , , , , , , , C4 633 , Mr y The shield-like pereopod 7 is comparable to Gammarella Bate (see Chevreux & Fage 1925 as Pherusa [=Nuuanu, =Colles/oej and Tabatzius McKinney and Barnard (1977), from the Caribbean Sea, but those genera differ from our new genus in the fully setose medial margins of the maxillae and the non-falcate article 3 of the mandibular palp lacking most D-setae, It is possible to build a plesio-morphic-apomorphic sequence of evolution from the base stock of Gammarella to Dumosus through loss of medial maxillary setae, reduction in mandibular palp article 3, loss of article 2 on the outer ramus of uropod 3, loss of major spines on inner plate of maxilliped, loss of several spines on the outer plate of maxilla I and retention of the primitive elongate inner ramus of uropod 3. The two genera (and the similar Tabatzius) share similar gnathopods, telson, pereopods, and many similarities in body form, head, antennae, mandibles, maxillipeds and pleon, 634 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON , , , , , P6 , , , , , , , , • , , , • , , , , , , , .' , , , . , y • P5 w Fig. 3. Dumosus atari. new species, holotype, male "x." . /", ." • R3 , , • • , • , , , , , '. • • -- --Pr T There is a superficial resemblance of Dumosus to Ceradocopsis (see Barnard and Karaman 1982), from the southern hemisphere, in the shortness of uropod 3, form of head, antennae, gnathopods, mandibles, maxilliped, uropods 1-2 and telson, but Ceradocospis has more medial maxillary setae, less shield-like pereopod 7 and bears an article 2 on the outer ramus of uropod 3. Dumosus atari, new species Figs. 1-3 Description of unique male, 1.96 mm. -Eyes composed of ochre-brown pig-ment mass with several clear, mostly anterior ommatidia extending outward, one detached gangliar ommatidium dorsally. Flagellum of antenna I shorter than articles 2-3 of peduncle combined. Article 4 of antenna 2 with weak apical hump; gland cone large, basal article smaiL • VOLUME 98, NUMBER 3 635 Mandibular incisors with articulate accessory tooth on medialmost edge, right and left rakers 3, with interrakers. Inner plate ofmaxilliped with scythe-like ventral coupling hook. Article 4 of gnathopod I pubescent; dactyls of gnathopods with apical nail and inner selUles. Pereopod 3 like illustration of pereopod 4 but slightly larger. Peduncle of pleopods elongate, usually with one lateral seta, 2 coupling hooks, rami extending equally, as long as peduncle, 5-articulate. Peduncle of uropod 2 with one 3picomedial spine. Holotype. -USNM 195138, male, 1.96 mm. Unique specimen with left per-eopod 5 missing. Type-locality. -Carrie Bow Cay, Belize, 24 Jun 1982, formalin wash of coral rubble from back reef, 0.5-1.0 m , coIl. J. D. Thomas. Remarks. - We have searched for this species again at Belize several times and in many other Caribbean localities to no avail; its clearly distinct generic position, and the excellent condition of the specimen makes it possible to describe. Acknowledgments We would like to thank the Scholarly Studies Program, administered by As-sistant Secretary for Science, Dr. David Challinor, Smithsonian Institution, for support during this study. The first author was also supported by NSF grant DEB8121128. Dr. KJaus RUtzler, Director of the Smithsonian Western Atlantic Mangrove Project (SWAMP) kindly provided field facilities in Belize. Mike Car-penter of the Smithsonian also provided the first author with invaluable assistance in the field. We would like to thank Linda B. Lutz, Mobile, Alabama, for inking the plates. Literature Cited Barnard , J. L. 1969. Gammaridean Amphipoda of the rocky intertidal of Cali fomi a: Monterey Bay to La lolla.-United States National Museum Bulletin 258:1-230, figs. 1-65. --, and G. S. Karaman. 1982. Classificatory revisions in Gammaridean Amphipods (Crustacea), part 2.-Proceedings of the BiologicarSociety of Washington 95(2):167-187 , fig. 1. Chevreux , L. , and L. Fage. 1925. Amphipodes.-Faune de France 9:1-488 , figs . 1-438. McKinney, L. D., and 1. L. Barnard. 1977. A new marine genus and species of the Nuuanu-group (Crustacea, Amphipoda) from the Yucatan peninsula.-Proceedings of the Biological Society of Washington 90:161-171 , 3 figs. Shoemaker, C. R. 1959. Three new cave amphip0ds from the West Indies. -loumal of the Wash-ington Academy of Sciences 49:273-283, figs. 1-4. (JDT) Newfound Harbor Marine Institute, Rt. 3, Box 170, Big Pine Key, Florida 33043; (JLB) Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution , Washington, D.C. 20560. 

A New Marine Genus of the Maera Group (Crustacea: Amphipoda) from Belize

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A New Marine Genus of the Maera Group (Crustacea: Amphipoda) from Belize

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