Naushonia serratipalma, Komai, Tomoyuki & Anker, Arthur, 2010

Komai, Tomoyuki & Anker, Arthur, 2010, Two new species of the laomediid genus Naushonia Kingsley, 1897 (Crustacea: Decapoda: Gebiidea) from the Indo-West Pacific, Zootaxa 2504, pp. 31-46 : 38-44

Naushonia serratipalma n. sp.

( Figs. 1 C; 5–7)

Material examined. Holotype: female (CL 4.5 mm), FLMNH UF Arthropoda 16437, French Polynesia, Society Archipelago, Moorea, Papetoai, snorkeling, lagoon, sand-silt with corals and rubble, depth 1–2 m, leg. A. Anker, 14.XI.2008.

Description of holotype. Body ( Fig. 1 C) moderately robust. Rostrum ( Fig. 5 A–D) strongly flattened dorsoventrally, generally rounded in dorsal view, slightly overreaching distal margin of second segment of antennular peduncle; lateral margins with row of numerous small spines increasing in size distally, terminal spine subequal in size to distal spines; dorsal surface with shallow median depression extending posteriorly to rostral base.

Carapace ( Fig. 5 A–D) subcylindrical, with distinct linea thalassinica extending over entire length; surface generally smooth, with few short setae. Postorbital spine simple, acuminate, with smooth mesial margin. Anterolateral margin spinulose, deeply notched just ventral to minute branchiostegal spine; pterygostomial angle acuminate. Gastric region convex, with five longitudinal carinae, including mid-dorsal carina interrupted by cervical groove, all carinae granulate; mid-dorsal carina low, anterior section starting from level of postantennal notch, posterior section not reaching to posterodorsal margin of carapace; submedian carinae slightly diverging posteriorly, extending from slightly posterior to orbital margin to about 0.4 carapace length; lateral carinae diverging posteriorly, extending from level of tip of postorbital spine to anterior 0.2 of carapace length. Cervical groove conspicuous, short, across about mid-length of carapace, not extending onto lateral surface.

Abdomen ( Fig. 5 E, F) with faint sculpture; ventral margin of pleura rounded. First somite unarmed on anterolateral margin; dorsal surface with obliquely transverse ridge interrupted medially, trace of mid-dorsal ridge on posterior half of tergum and trace of oblique lateral carina; pleuron moderately large. Second somite with traces of mid-dorsal ridge and obliquely transverse ridges adjacent to posterodorsal margin, as well as trace of lateral carina; pleuron nearly symmetrical. Third somite with traces of mid-dorsal and lateral ridges. Fourth somite with trace of mid-dorsal ridge, trace of transverse depressions on either side of midline, and trace of two lateral ridges. Fifth somite with trace of mid-dorsal ridge and rounded depressions on either side of midline; lateral ridge rather distinct. Sixth somite slightly widened posteriorly, with flared posteroventral margins bearing low squamiform tubercles on dorsal surface; posterolateral process blunt. Telson 1.3 times longer than wide, rounded posteriorly, with pair of minute lateral spines arising posterior to level of midlength; lateral margin anterior to lateral spine straight, slightly converging posteriorly; dorsal surface with minute scattered tubercles; posterior margin fringed with stiff setae increasingly longer posteriorly.

Eyes ( Fig. 5 D) short, wider than long; cornea darkly pigmented, narrower than eyestalk, hardly visible in dorsal view; eyestalk without tubercle or spine on distomesial margin.

Antennular peduncle ( Fig. 5 C, D) short, nearly reaching distal margin of fifth segment of antennal peduncle. First segment not visible in dorsal view, nearly as long as distal two segments combined, armed with minute distolateral and small ventromesial distal spines ( Fig. 5 G); dorsal surface with statolith opening closed by stiff setae. Second segment with minute distolateral spine. Third segment unarmed distolaterally. Lateral flagellum slightly longer than peduncle, composed of 13 articles; mesial flagellum about 0.7 length of lateral flagellum, composed of eight articles.

Antennal peduncle ( Fig. 5 C, D, H) stout. First segment with smooth ventrodistal margin. Second segment with row of three small spines on distolateral margin. Third segment with small subdistal spine on ventromesial margin. Fourth and fifth segments each with distolateral spine; fifth segment wider than long. Antennal scale moderately broad, short, overreaching mid-length of third peduncular segment; lateral margin slightly convex, armed with six sharp spines (including terminal spine) in distal 0.7 of its length, spines subequal in size; mesial margin strongly convex, with row of stiff setae; dorsal surface with low longitudinal carina. Antennal flagellum longer than body; articles with several short to moderately long setae on distal margins.

Epistomial horn ( Fig. 5 G) relatively slender, almost reaching distal margin of the first segment of antennular peduncle.

Mouthparts not dissected. Third maxilliped ( Fig. 7 A) with moderately stout endopod composed of five segments. Coxa with setobranch composed of numerous stiff long setae; ventromesial margin with one spinule ( Fig. 7 B). Basis short, with one prominent spine and two spinules on mesial surface ( Fig. 7 B). Ischium ( Fig. 7 B) slightly widened distally, distodorsal angle only slightly produced; ventral margin carinate, with row of spinules; crista dentata well developed, with row of sharp spines. Merus shorter than ischium, with small distodorsal and ventromesial spines; dorsolateral margin also with two spinulose tubercles ( Fig. 7 C); ventral margin spinulose. Carpus short, distodorsal margin not projecting. Propodus slightly longer than dactylus. Dactylus tapering into blunt tip, with thick cluster of setae on flexor surface. Exopod slender, proximal article reaching distal margin of ischium, distal article short, biarticulated, flexed against proximal article; flagellum short, but well developed. Epipod large, margins with sharp denticles; mastigobranch well developed; podobranch consisting of numerous, slender lamella.

First pereopods (= chelipeds) ( Figs. 1 C, 6A–D) strong, subchelate, equal in size, symmetrical in shape, strongly flattened dorsoventrally. Ischium widened distally; mesial surface flanked by clearly delimited dorsomesial and ventromesial margins, both with row of numerous spinules; lateral margin carinate, with row of minute spinules. Merus widened distally, cross section nearly triangular; distomesial angle produced in relatively narrow, rounded lobe, bearing small marginal spines; lateral margin bluntly carinate, ending in small spine distally, with row of minute spinules over entire length; mesial face narrow, flanked by sharply delimited dorsomesial and ventromesial margins; dorsomesial and ventromesial margins with row of minute spinules, latter continuing to distomesial lobe; ventral surface bluntly elevated along midline, ventromesial face smooth. Carpus short, slightly widened distally; dorsal surface minutely granular, distodorsal margin minutely denticulate, dorsolateral margin sharply delimited, bearing row of numerous spinules; lateral surface almost smooth; ventral surface slightly elevated along midline, distoventral and mesial margins smooth. Palm elongate subovate in general outline, rhomboidal in cross-section, about twice as long as wide (including fixed finger), subequal in length to ischium and merus combined; dorsal surface nearly smooth, weakly elevated along midline, sparsely granular; lateral margin carinate, with row of numerous spinules increasing in size distally and some scattered setae; mesial margin sharply carinate, serrated with row of spinules, and with sparse row of setae; ventral surface weakly elevated along midline, nearly smooth; fixed finger arising slightly proximal to palm mid-length; cutting edge strongly oblique, distal half with row of sharp teeth decreasing in size distally (proximal three teeth prominent, posteriormost tooth larger than fixed finger), proximal half serrated with sharp, slender spines of similar length; submarginal row of spinules present on dorsal surface along proximal serrated margin of cutting edge. Dactylus moderately slender, slightly curved, closing completely against cutting edge, tip overlapping dorsal surface of palm when closed; dorsal (extensor) margin with row of setae, proximal part not particularly expanded; ventral (flexor) margin sharply carinate.

Second pereopod ( Fig. 7 D) stout, simple. Merus with sparse row of elongate setae on ventral margin. Carpus about 0.4 times as long as merus. Propodus slightly wider than long, slightly shorter than carpus. Dactylus ( Fig. 7 E, F) lanceolate, terminating in acute unguis; dorsal margin arcuate in mesial view; dorsal surface with dense, more or less elongate serrate setae; ventral margin minutely pectinate in distal 0.7 of its length.

Third to fifth pereopods similar, decreasing in length posteriorly. Third pereopod ( Fig. 7 G) with ischium having smooth dorsal and ventral margins, both with scattered short setae; merus slightly narrowed distally, 4.4 times longer than wide, unarmed; carpus about 0.4 times as long as merus; propodus with ventral margin bearing row of stiff setae decreasing in length distally; dactylus ( Fig. 7 J) 0.5 times as long propodus, about 4.8 times longer than wide, ending in slender unguis, lateral surface unarmed, ventral margin with comb-like, toothed lamella on proximal 0.7 of its length. Fourth and fifth pereopods as illustrated ( Fig. 7 H–K).

Branchial formula identical with previous species (see Table 1 ). Epipod on fourth pereopod small, without marginal denticles.

First pleopod small, slender, biarticulated. Second to fifth pleopods biramous, rami slender, lanceolate, subequal, without appendix interna.

Uropod ( Fig. 7 M) with spinulose transverse suture on both exopod and endopod. Exopod with three spinules on distal half of lateral margin, with long movable spine at posterolateral angle; dorsal surface with two longitudinal ridges, each bearing several minute spinules. Endopod with lateral margin smooth, with one movable spine at posterolateral angle; dorsal surface with low median ridge, bearing some minute spinules. Protopod with serrated posterodorsal margin.

Colour in life. Uniform opaque-whitish with pale yellowish tinge; gonads orange ( Fig. 1 C).

Distribution. Presently known only from the type locality in Moorea, Society Archipelago, French Polynesia, southwestern Pacific Ocean.

Habitat. Shallow sandy lagoon with some large coral heads, coral rubble and holothurians ( Holothuria atra Jaeger, 1833 ), depth: 1– 2 m.

Etymology. Name referring to the serrated lateral and mesial margins of the cheliped palm ( serratipalma = serrated palm in Latin). Used as a noun in apposition.

Remarks. Naushonia serratipalma n. sp. is morphologically closest to N. japonica , N. perrieri and the above described N. latimana n. sp. Characters useful for separation of these four species are presented in Table 2.

Figures

FIGURE 1. Habitus in dorsal view. A, Naushonia latimana n. sp., holotype, male (CL 3.4 mm), FLMNH UF Arthropoda 13630, Mayotte, Comoro Archipelago; B, same species, paratype, female (CL 3.3 mm), FLMNH UF Arthropoda 13609, same locality as holotype; C, Naushonia serratipalma n. sp., holotype (CL 4.5 mm), FLMNH UF Arthropoda 16437, Moorea, Society Archipelago, French Polynesia.

FIGURE 5. Naushonia serratipalma n. sp., holotype, female (CL 4.5 mm), FLMNH UF Arthropoda 16437. A, carapace, dorsal view; B, same, lateral view; C, anterior part of carapace and cephalic appendages, dorsal view (antennal flagella omitted; setae partially omitted); D, same, lateral view; E, abdomen and telson, dorsal view; F, same, lateral view; G, basal segment of left antennular peduncle and epistomal horn, ventral view; H, left antennal peduncle, ventral view. Scale bars: 1 mm for A, B, E, F; 0.5 mm for C, D, G, H.

FIGURE 7. Naushonia serratipalma n. sp., holotype, female (CL 4.5 mm), FLMNH UF Arthropoda 16437. A, left third maxilliped, lateral view; B, basis and ischium of left third maxilliped, dorsal view; C, carpus of left third maxilliped, mesial view; D, left second pereopod, lateral view; E, propodus and dactylus of left second pereopod, mesial view; F, same, mesial view; G, left third pereopod, lateral view; H, left fourth pereopod, lateral view; I, left fifth pereopod, lateral view; J, K, dactyli of left third and fourth pereopods, lateral view; L, propodus and dactylus of left fifth pereopod, lateral view; M, right uropod, dorsal view (perpendicular). Scale bars: 0.5 mm.