Description of a new genus and two new species of alpheid shrimps from Guam (Crustacea, Decapoda) * Author Anker, Arthur text Zootaxa 2010 2372 389 404 journal article 37550 10.5281/zenodo.275825 4d245414-8e23-43d2-8ccf-7d1d83a8953b 1175-5334 275825 Bruceopsis guamensis sp. nov. ( Figs. 1 C, 6–8) Type material. Holotype : female (cl 7.7 mm , tl 22.6 mm , dissected), FLMNH UF Arthropoda 10947 , Mariana Islands , Guam , Agat Bay north of Alutom Islet , under rocks , 3–7 m , coll. H.T. Conley , 2000-2001 (exact date unknown) [ UGML-0455 , ZZZ 16669 ]. Description. Body not particularly slender, moderately compressed ( Fig. 1 C). Carapace smooth, sparsely covered with stubby setae ( Figs. 1 C, 6B); cardiac notch well developed ( Fig. 1 C). Frontal margin with rostrum and orbital teeth; rostrum well developed, thickened, acuminate, longer than wide, tip reaching slightly beyond distal margin of first segment of antennular peduncle, with marked lateral ridge and convex ventral margin; orbital teeth blunt, not protruding beyond rostral base, ( Figs. 6 A –B). Pterygostomial margin slightly projecting anteriorly, bluntly angular ( Fig. 6 B). Eyes completely concealed by orbital hoods, anteriormost portion of cornea visible in lateral view; cornea well pigmented, anteromesial surface without dorsal process. Epistomial sclerites with sharp ventrally directed teeth. Abdomen with second pleomere conspicuously enlarged in female ( Fig. 1 C); third and fourth pleomeres with rounded posteroventral angle; fifth pleomere with posteroventral region angular, not projecting; sixth abdominal somite not elongate, with subtriangular, non-projecting articulated plate at posteroventral angle ( Figs. 1 C); posterolateral angle subacutely produced. Telson subrectangular, tapering posteriorly, about twice as long as wide at base; dorsal surface with two pairs of strong dorsal spines inserted at about mid-length and 0.75 length of telson, respectively ( Fig. 6 G); posterior margin slightly convex, with two pairs of stout posterolateral spines, lateral much shorter and slenderer than mesial; margin between posterolateral spines with 12 plumose setae ( Fig. 2 J); anal tubercles absent. Antennular peduncle robust; first segment with strong acuminate stylocerite, reaching well beyond midlength of third segment ( Fig. 6 A –B); mesioventral carina with strong compressed tooth ( Fig. 6 C); second segment subquadrate in dorsal view, somewhat shorter than first; third segment about the same length as second; lateral flagellum thicker than mesial, bifurcating at fourth segment, secondary ramus well developed, elongate, without visible segmentation; tufts of aesthetascs present on ventral margin from first segment to tip of secondary ramus ( Fig. 6 D). Antenna with stout basicerite, armed with anteriorly projecting, sharp distolateral tooth ( Fig. 6 B); carpocerite short, moderately stout, not exceeding scaphocerite; scaphocerite reaching past distal end of antennular peduncle, ovate, with strong, acute distolateral tooth; blade broad, with strongly convex anterior margin, not exceeding distolateral tooth ( Fig. 6 A ); flagellum narrower than lateral antennular flagellum, but stouter than mesial antennular flagellum. Mouthparts ( Fig. 7 A –F) typical for family, except maxillule. Mandible with bisegmented palp; incisor process well developed, with about 12 teeth, centrally situated teeth stronger ( Fig. 7 A ); molar process well developed, with distal ridge, protuberances and dense rows of stiff setae. Maxillule with bilobed palp ( Fig. 7 B), lower lobe with unusually thick seta ( Fig. 7 C); upper lobe with one much slenderer seta. Maxilla with small, unsegmented palp (endopod); basal endite with deep cleft; scaphognathite rather narrow ( Fig. 7 D). First maxilliped with trisegmented palp (endopod), distally fringed with long plumose setae; caridean lobe of exopod poorly developed ( Fig. 7 E); epipod bilobed. Second maxilliped with epipod oval, not elongate ( Fig. 7 F). FIGURE 6. Bruceopsis guamensis sp. nov. , holotype, female (FLMNH UF Arthropoda 10947): A, frontal region, dorsal view; B, same, lateral view; C, tooth on mesioventral carina of first segment of antennular peduncle, lateral view; D, antennular flagella, lateral view; E, cardiac notch, lateral view; F, uropod, dorsal view; G, telson, dorsal view; H, same, detail of posterior margin. FIGURE 7. Bruceopsis guamensis sp. nov. , holotype, female (FLMNH UF Arthropoda 10947): A, mandible, mesial view; B, maxillule, lateral view; C, same, detail of palp; D, maxilla, lateral view (ventral portion of scaphognathite damaged); E, first maxilliped, lateral view; F, second maxilliped, lateral view; G, third maxilliped, lateral view (mastigobranch damaged, not drawn); H, same, tip of ultimate segment, dorsomesial view. Third maxilliped pediform, slender ( Fig. 7 G); coxa with lateral plate somewhat produced distally; exopod well developed, reaching distal end of antepenultimate segment, with long flexible setae basally; antepenultimate segment slender, compressed, somewhat depressed on ventral margin, setose; penultimate segment less than 0.35 length of antepenultimate segment, about twice as long as wide; ultimate segment elongate, tapering distally, with rows of serrate setae, ending in subacute corneous tip, with two stout subdistal spines ( Fig. 7 H); arthrobranch well developed. FIGURE 8. Bruceopsis guamensis sp. nov. , holotype, female (FLMNH UF Arthropoda 10947): A, left cheliped, lateral view; B, same, chela, ventrolateral view; C, same, carpus, mesial view; D, second pereiopod, lateral view; E, same, last carpal segment and chela, mesial view; F, third pereiopod, lateral view; G, same, dactylus, mesial view; H, fifth pereiopod, lateral view. First pereiopods (chelipeds) equal in size, symmetrical in shape, feebly enlarged in comparison with other alpheid genera ( Fig. 1 C); coxa with rounded dorsal protuberance near basis ( Fig. 8 A ), ischium slender, with slender spinule on distodorsal margin; merus relatively slender, about 4.5 times as long as wide, unarmed, ventral margin somewhat depressed distally, mesioventral margin without setal rows distally; carpus short, cup-shaped, slightly constricted dorsally, with comb-like row of setae on mesial face ( Fig. 8 C); chela with palm smooth, rounded in cross-section; fingers about 0.8 times length of palm, not particularly modified, straight, furnished with elongate setae; cutting edge of dactylus with some irregularly shaped teeth around mid-length; cutting edge of pollex with at least four rounded regularly spaced teeth in proximal half; distal portions of both fingers unarmed ( Fig. 8 B). Second pereiopod not especially elongate, slender, ischium slightly longer than merus; carpus fivesegmented, with ratio approximately equal to 2.5:1:1:1:1.5 ( Fig. 8 D); chela longer than distal-most carpal segment, simple ( Fig. 8 E). Third pereiopod slender; ischium with two spines in sockets; merus about 6.5 times as long as wide, unarmed; carpus about half-length of merus, distoventral margin unarmed; propodus slightly longer than merus, ventral margin with four slender spines in addition to longer distal spine adjacent to dactylus ( Fig. 8 F); dactylus slender, conical, slightly curved, simple, dorsal margin with one slight notch distal to dactylus mid-length and one more conspicuous notch (forming a small tooth) at 0.65 length of dactylus ( Fig. 8 G). Fourth pereiopod generally very similar to third. Fifth pereiopod with unarmed ischium; merus and carpus similar to those of third pereiopod, propodus with six spinules on ventral margin and ventrolateral brush consisting of 13 or so short setal rows ( Fig. 8 H); dactylus generally similar to that of third pereiopod, with two small notches on dorsal margin. First pleopod of female biramous, endopod about 0.4 length of exopod, moderately slender; apex and proximal margin fringed with setae. Second pleopod of female biramous, without specific features; endopod with appendix interna. Uropod with ovate endopod, exopod ovate mesially, with almost straight lateral margin; protopod with strong tooth on lateral lobe, distally subdivided into large lateral acuminate point and small blunt mesial angle; diaeresis with large tooth adjacent to distolateral tooth; distolateral spine strong, elongate, reaching distal margin of exopod ( Fig. 6 F). Gill/exopod formula as given for genus. Colour pattern not recorded. Size. Holotype , ovigerous female, cl 7.7 mm , tl 22.6 mm . Etymology. The name of this new species refers to the type locality, Guam , Mariana Islands . Ecology. The only available field notes indicate that the shrimp was collected under rocks, at 3–7 m , possibly on fore-reef or reef slope (see Remarks for B. projectus sp. nov. ). Distribution. Presently known only form the type locality, Agat Bay, north of Alutom Islet, Guam , Mariana Islands . Remarks. Bruceopsis guamensis sp. nov. differs from its only congener, the above-described B. projectus sp. nov. by a number of characters, including the non-projecting blunt orbital teeth ( Fig. 6 A , cf. Fig. 2 A ); the eyes being completely covered by the orbital hoods ( Fig. 6 A , cf. Fig. 2 A ); the distinctly longer stylocerite ( Fig. 2 A , cf. Fig. 6 A ); the smaller, equal, and symmetrical chelipeds ( Fig. 1 C, cf. Fig. 1 B); the non-projecting articulated plate of the sixth pleonite ( Fig. 1 C, cf. Figs. 1 B; 2E, G); the absence of a sharp point at the posteroventral angle of the third pleuron ( Fig. 1 C, cf. Fig. 1 B); the absence of a small tooth on the eyes ( Figs. 6 A , cf. Fig. 2 A ); the lower lobe of the maxillular palp furnished with an unusually stout seta ( Fig. 7 C, cf. Fig. 3 C) — a feature unique in the family Alpheidae and possibly within the Caridea.