Bruceopsis guamensis, Anker, Arthur, 2010

Anker, Arthur, 2010, Description of a new genus and two new species of alpheid shrimps from Guam (Crustacea, Decapoda) *, Zootaxa 2372, pp. 389-404 : 399-403

publication ID	https://doi.org/ 10.5281/zenodo.275825
DOI	https://doi.org/10.5281/zenodo.6204664
persistent identifier	https://treatment.plazi.org/id/038E1764-FF95-F423-FF5D-FE2CF97304C1
treatment provided by	Plazi
scientific name	Bruceopsis guamensis
status	sp. nov.

Treatment

Bruceopsis guamensis View in CoL sp. nov.

( Figs. 1 View FIGURE 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 View FIGURE 1 C). Carapace smooth, sparsely covered with stubby setae ( Figs. 1 View FIGURE 1 C, 6B); cardiac notch well developed ( Fig. 1 View FIGURE 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 View FIGURE 6 A –B). Pterygostomial margin slightly projecting anteriorly, bluntly angular ( Fig. 6 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 2 J); anal tubercles absent.

Antennular peduncle robust; first segment with strong acuminate stylocerite, reaching well beyond midlength of third segment ( Fig. 6 View FIGURE 6 A –B); mesioventral carina with strong compressed tooth ( Fig. 6 View FIGURE 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 View FIGURE 6 D). Antenna with stout basicerite, armed with anteriorly projecting, sharp distolateral tooth ( Fig. 6 View FIGURE 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 View FIGURE 6 A); flagellum narrower than lateral antennular flagellum, but stouter than mesial antennular flagellum.

Mouthparts ( Fig. 7 View FIGURE 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 View FIGURE 7 A); molar process well developed, with distal ridge, protuberances and dense rows of stiff setae. Maxillule with bilobed palp ( Fig. 7 View FIGURE 7 B), lower lobe with unusually thick seta ( Fig. 7 View FIGURE 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 View FIGURE 7 D). First maxilliped with trisegmented palp (endopod), distally fringed with long plumose setae; caridean lobe of exopod poorly developed ( Fig. 7 View FIGURE 7 E); epipod bilobed. Second maxilliped with epipod oval, not elongate ( Fig. 7 View FIGURE 7 F).

Third maxilliped pediform, slender ( Fig. 7 View FIGURE 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 View FIGURE 7 H); arthrobranch well developed.

First pereiopods (chelipeds) equal in size, symmetrical in shape, feebly enlarged in comparison with other alpheid genera ( Fig. 1 View FIGURE 1 C); coxa with rounded dorsal protuberance near basis ( Fig. 8 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 8 D); chela longer than distal-most carpal segment, simple ( Fig. 8 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 6 A, cf. Fig. 2 View FIGURE 2 A); the eyes being completely covered by the orbital hoods ( Fig. 6 View FIGURE 6 A, cf. Fig. 2 View FIGURE 2 A); the distinctly longer stylocerite ( Fig. 2 View FIGURE 2 A, cf. Fig. 6 View FIGURE 6 A); the smaller, equal, and symmetrical chelipeds ( Fig. 1 View FIGURE 1 C, cf. Fig. 1 View FIGURE 1 B); the non-projecting articulated plate of the sixth pleonite ( Fig. 1 View FIGURE 1 C, cf. Figs. 1 View FIGURE 1 B; 2E, G); the absence of a sharp point at the posteroventral angle of the third pleuron ( Fig. 1 View FIGURE 1 C, cf. Fig. 1 View FIGURE 1 B); the absence of a small tooth on the eyes ( Figs. 6 View FIGURE 6 A, cf. Fig. 2 View FIGURE 2 A); the lower lobe of the maxillular palp furnished with an unusually stout seta ( Fig. 7 View FIGURE 7 C, cf. Fig. 3 View FIGURE 3 C) — a feature unique in the family Alpheidae and possibly within the Caridea.