Epipontonia tahitiensis, Bruce, 2004

Bruce, A. J., 2004, A new pontoniine shrimp from Tahiti, French Polynesia (Crustacea, Decapoda, Palaemonidae), Zoosystema 26 (2), pp. 279-289 : 280-286

publication ID	https://doi.org/ 10.5281/zenodo.10113003
persistent identifier	https://treatment.plazi.org/id/286B1505-4D3E-2B3C-FED9-FA87FB64F923
treatment provided by	Marcus
scientific name	Epipontonia tahitiensis
status	sp. nov.

Treatment

Epipontonia tahitiensis View in CoL n. sp.

( Figs 1-4 View FIG View FIG View FIG View FIG )

HOLOTYPE. — French Polynesia. Tahiti, stn S(?) 11, 1982, coll. O. Odinetz, 1 ovig. ( MNHN Na. 15021). ETYMOLOGY. — Named after the locality of discovery: Tahiti.

DIAGNOSIS. — Rostral dentition 6/1, supraorbital or paraorbital spines absent, incisor process of mandible well developed with numerous small teeth, second maxilliped with epipod, second pereiopods similar, unequal, third ambulatory dactyl biunguiculate, corpus and unguis ventrally denticulate.

DESCRIPTION

Small sized pontoniine shrimp of subcylindrical body form, in general closely resembling previously described species of the genus.

Rostrum ( Fig. 1B View FIG ) compressed, about 0.44 of CL, 7 times longer than deep, slightly depressed, reaching to level of distal segment of antennular peduncle, with six small acute dorsal teeth, with one to three interdental setae, ventral border straight, non-setose, with single small preterminal ventral tooth.

Carapace ( Fig. 1A View FIG ) smooth, glabrous, without epigastric, supraorbital and hepatic spines, orbit feebly developed, antennal spine well developed, submarginal, overlying small inferior orbital angle, anteroventral margin of branchiostegite produced, rounded.

Abdomen without special features, pleura round- ed, sixth segment ( Fig. 1I View FIG ) strongly depressed, with small posterolateral process with acute upper tooth, ventrolateral process broadly expanded, posterolaterally acute.

Telson ( Fig. 1J View FIG ) about 1.8 times sixth segment length, 0.55 of CL, 2 times longer than width, lateral margins convex, convergent, with two pairs of large submarginal dorsal spines ( Fig. 1L View FIG ), about 0.2 of telson length, at 0.2 and 0.5 of telson length, posterior margin ( Fig. 1K View FIG ) rounded, without median process, lateral spines small, 0.5 of dorsal spine length, intermediate spines robust, about 0.25 of telson length, submedian spines long, slender, non-setulose, slightly shorter than intermediate spines.

Antennule ( Fig. 1C View FIG ) with proximal segment ( Fig. 1D View FIG ) with medial length 1.7 times longer than width, medial margin straight, non-setose, lateral margin feebly concave, with large acute distolateral lobe reaching beyond level of proximal dorsal margin of second segment, stylocerite broad, acute, reaching to about 0.45 of segment length, statocyst well developed, without statolith, ventromedial border with small acute tooth at about 0.5 of length; intermediate and distal segments short, subequal, combined equal to about 0.5 of proximal segment length; upper flagellum biramous, proximal three segments of rami fused, shorter free ramus with one segment, longer with five segments, with six groups of paired aesthetascs, each with a small black pigment spot ( Fig. 1E View FIG ) at about 0.2 of length; lower flagellum short with nine segments.

Antenna ( Fig. 1F View FIG ) with basicerite robust, with long acute distolateral tooth, ischiocerite and merocerite short; carpocerite about 3.4 times longer than central width, reaching to about 0.6 of lamellar length of scaphocerite; flagellum short; scaphocerite ( Fig. 1G View FIG ) well developed, reaching to level of end of antennular peduncle, lamella about 2.5 times longer than width, anterior margin broadly convex, lateral margin sublinear with strong acute distolateral tooth, about 0.3 of lamella length, far exceeding lamellar margin.

Eye ( Fig. 1H View FIG ) with oblique globular cornea, without accessory pigment spot; stalk about as long as wide, tapering slightly distally.

Mandible ( Fig. 2A View FIG ) slender, without palp; incisor process ( Fig. 4B View FIG ) distally convex, with 12 small acute teeth, of decreasing size proximally; molar process ( Fig. 4C View FIG ) subcylindrical, distally truncate, with large acute tooth ventrally, dorsally carinate with upper and lower simple spines. Maxillula ( Fig. 2B View FIG ) normal, with bilobed palp ( Fig. 4D View FIG ), upper lobe small, lower lobe elongate, with small simple seta distally; upper lacinia broad, with 10 short stout serrulate spines and simple setae distally; lower lacinia short, subcylindrical, with numerous setae distally and ventrally. Maxilla ( Fig. 2C View FIG ) with elongate palp, with distal seta, with few short proximolateral setae; basal endite bilobed, lobes short, broad, each with about 14 simple setae distally, coxal endite obsolete, medial margin convex; scaphognathite broad, 2.5 times longer than central width. First maxilliped ( Fig. 2D View FIG ) with subcylindrical non-setose palp, basal and coxal endites fused, broad, medial margin straight with numerous slender simple setae, exopod with well developed small caridean lobe, slender flagellum, with four plumose terminal setae, with small feebly bilobed epipod laterally. Second maxilliped ( Fig. 2E View FIG ) of normal form, dactylar segment narrow, with numerous slender spiniform setae medially; exopod normal with four plumose terminal setae, coxa produced medially, with two slender setae; with small rounded epipod laterally, without podobranch. Third maxilliped ( Fig. 2F View FIG ) with endopod normal, ischiomerus and basis feebly separated, combined segment about 4.2 times longer than central width, tapering slightly distally, sparsely provided with slender simple setae medially, intermediate segment about half of combined antepenultimate segment length, subcylindrical, 3.3 times longer than width, medial margin with few robust spiniform setae; terminal segment about 0.66 of preterminal segment length, tapering distally, 3 times longer than proximal width, with long spiniform seta distally, subequal to segment length, with proximoventral serrulations, medial margin with numerous spiniform setae; exopod normal, with slender flagellum with four plumose terminal setae; coxa not medially produced, with rounded epipod laterally, without arthrobranch. Paragnaths ( Fig. 2G View FIG ) rounded, simple, deeply divided.

First pereiopod ( Fig. 3A View FIG ) normal, extending beyond rostrum by distal third of merus, chela ( Fig. 3B View FIG ) with palm 3 times longer than deep, sub-oval in section, distal two thirds slightly tapering, fingers ( Fig. 4E View FIG ) 0.4 of palm length, sparsely setose, dactylus 4 times longer than proximal depth, subspatulate laterally, cutting edge entire, tips ( Fig. 4F View FIG ) bidentate, teeth simple, fixed finger similar; carpus 1.25 times chela length, 6.5 times longer than distal width, subcylindrical; merus 0.95 of carpal length, 5 times longer than central width; ischium subequal to chela length; basis and coxa normal, coxa with small setose medial process.

Second pereiopods similar, unequal. Major second pereiopod ( Fig. 3C View FIG ) with chela ( Fig. 3E View FIG ) about 1.3 of CL, palm compressed curved dorsally ( Fig. 3D View FIG ), generally smooth, with small acute denticles along ventral margin, glabrous, 1.7 times longer than central depth, dactylus ( Fig. 4G View FIG ) about 0.4 of palm length, 2.7 times longer than deep, dorsal margin strongly convex, tip broadly acute, cutting edge sharp, entire, feebly convex, fixed finger similar, slightly shorter, stout broad acute tip, cutting edge deeply channeled, medial and lateral edges concave, entire; carpus about 0.35 of palm length, broadly expanded distally, smooth, unarmed; merus 0.45 of palm length, 2.1 times longer than central width, slightly expanded centrally, ventral margin with four small acute teeth, ischium subequal to meral length, 2.6 times longer than distal width, tapering proximally, ventral margin unarmed; basis and coxa without special features. Minor second pereiopod with chela ( Fig. 3F View FIG ) subequal to CL, 0.7 of major chela length, palm 1.9 times longer than deep, compressed, ventral border with numerous small acute denticles and long simple setae, fingers ( Fig. 4H View FIG ) about 0.47 of palm length, dactylus 2.3 times longer than central depth; proximal segments as in major chela, slightly smaller.

Third pereiopod ( Fig. 3G View FIG ) normal, dactyl ( Fig. 4I View FIG ) compressed, unguis distinctly demarcat- ed, 3 times longer than oblique basal width, with single small spinule proximodorsally, curved, ventral border concave with three small acute denticles; corpus twice as long as proximal depth, with pairs of sensory setae distally, biunguiculate with large acute distoventral tooth, ventral margin slightly concave with four smaller acute teeth; propod ( Fig. 3H View FIG ) about 0.43 of CL, subuniform, compressed, about 5 times longer than wide, with single stout distoventral spine, subsequal to basal width of corpus, five similar equally spaced ventral spines and single smaller proximal ventral spine; carpus 0.66 of propod length, unarmed; ischium 1.16 of propod length, 3.4 times longer than wide, unarmed; ischium 0.77 of propod length, unarmed; basis and coxa without special features.

Fourth pereiopod similar to third pereiopod; dactyl ( Fig. 4J View FIG ) distally damaged(?), unguis without dorsal spinule, not clearly demarcated, otherwise similar, corpus biunguiculate with single small acute distoventral tooth only; propod ( Fig. 3I View FIG ) about 0.9 of third propod length, 5.4 times longer than deep, with single more slender distoventral spine, four ventral spines of diminishing size proximally; other segments without special features.

Fifth pereiopod similar to third pereiopod; dactyl ( Fig. 4K View FIG ) with clearly demarcated unguis without dorsal spinule, ventral margin with three denticles; corpus biunguiculate, with very small acute distoventral tooth only; propod ( Fig. 3J View FIG ) 1.06 of third propod length, 6.7 times longer than proximal depth, without spines, with numerous slen- der distoventral setae; other segments without special features.

Uropod ( Fig. 1M View FIG ) with protopodite posterolaterally unarmed; exopod 0.9 of telson length, 2.2 times longer than broad, lateral margin nonsetose, convex proximally, distally straight, with strong distolateral tooth ( Fig. 4L View FIG ), with robust spine medially, diaeresis obsolete; endopod subequal to exopod length, 2.4 times longer than width.

Ova normal, 13.

Measurements (in mm)

Total body length, c. 5.9; postorbital carapace length, 1.45; carapace and rostrum, 2.2; major second pereiopod, chela, 1.9; minor second pereiopod, chela, 1.4; length of ovum, 0.5.

Coloration and host

No data.

Systematic position

Epipontonia tahitiensis View in CoL n. sp. is not closely relat- ed to the three previously described species of the genus, differing from all three in possessing an unreduced mandibular incisor process and an epipod on the second maxilliped, although the mandible of E. hainanensis Li, 1999 View in CoL has not yet been illustrated in detail. In all other features it conforms closely to the generic description.

REMARKS

Epipontonia tahitiensis View in CoL n. sp. is completely without the remarkably ornate first pereiopod finger tips found in E. anceps Bruce, 1983 View in CoL . In this species the finger tips are provided with long slender serrulate terminal spines flanked by denticulate medial and lateral expansions. These are also lacking in E. anceps View in CoL and E. hainanensis View in CoL .