Ancylomenes luteomaculatus, Okuno & Bruce, 2010

Okuno, J. & Bruce, A. J., 2010, Designation of Ancylomenes gen. nov., for the ‘ Periclimenes aesopius species group’ (Crustacea: Decapoda: Palaemonidae), with the description of a new species and a checklist of congeneric species *, Zootaxa 2372 (1), pp. 85-105 : 88-96

publication ID	https://doi.org/ 10.11646/zootaxa.2372.1.11
persistent identifier	https://treatment.plazi.org/id/6151A570-FFD3-FFBF-FF2B-FAB6FF02FCBD
treatment provided by	Felipe
scientific name	Ancylomenes luteomaculatus
status	sp. nov.

Treatment

Ancylomenes luteomaculatus View in CoL sp. nov.

( Figs. 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 , 6A–B View FIGURE 6 )

Periclimenes cf. venustus View in CoL . — Debelius 1999: 179, unnumbered figs. Not Periclimenes venustus Bruce, 1990 View in CoL (see Remarks).

Periclimenes sp. D . — Kawamoto & Okuno 2003: 45, unnumbered figs. (see Remarks).

Periclimenes sp. — Fransen 2004: 21, unnumbered fig. (see Remarks).

Material examined. Holotype. CMNH-ZC 02200 , male, CL 3.6 mm, off Gima Harbor , Kume-jima Island , Ryukyu Islands, Japan, 26º19.7’N, 126º45.6’E, 32 m, associated with Pachycerianthus sp. , 13 November 2002, leg. J. Okuno and T. Kawamoto GoogleMaps . Paratypes. Ryukyu Islands . CMNH-ZC 02372 , 1 male, CL 3.3 mm, 1 male, CL 3.4 mm, 1 female, CL 3.0 mm, same data as holotype. Philippines. QM W28900, AMPI 1494 , 1 ov. female, CL 4.7 mm, Anilao, Batangas Bay, Luzon, 27 m, associated with “tube anemone”, 9 April 2004, leg. N. Coleman. GoogleMaps

Description of male and small female. Medium sized pontoniine shrimp of subcylindrical body form ( Fig. 1 View FIGURE 1 ).

Carapace ( Fig. 1 View FIGURE 1 ) smooth, glabrous; orbit ( Fig. 2B View FIGURE 2 ) feebly developed, inferior orbital angle strongly produced, acute, with reflected ventral inner flange; antennal spine well developed, slender, submarginal, arising with distinct interval from inferior orbital angle; hepatic spine large, arising slightly ventral to level of antennal spine; median carina armed with single postrostral tooth; supraorbital spine absent; pterygostomial angle blunt.

Rostrum ( Fig. 2B View FIGURE 2 ) slender, almost straight, 0.9–1.1 times as long as carapace, reaching or slightly overreaching level of midlength of distal segment of antennular peduncle; dorsal margin armed with 7–9 equidistant, small, acute teeth, interspaced by short plumose setae, distal part unarmed; ventral margin with carina obsolete, fringed with row of long plumose setae, subterminally armed with 1 or 2 small, acute teeth; lateral carina obsolete.

Abdomen ( Fig. 1 View FIGURE 1 ) smooth, glabrous; pleura of first to third somites broad, second pleuron roundly expanded. Posteroventral margin of fourth and fifth somites with pleura produced posteriorly, rounded. Posterior third of median carina of third tergum strongly elevated, subcarinate. Sixth somite elongate, 1.2–1.3 times as long as carapace, 1.3–1.4 times as long as telson, posterolateral process acute, posteroventral margin produced, acute. Telson ( Fig. 2D View FIGURE 2 ) 0.9–1.0 times as long as carapace, gradually tapering posteriorly to posterior margin with midpoint convex; dorsal surface armed with 2 pairs of small, submarginal spines at 0.5 and 0.7 of telson length; posterior margin ( Fig. 2E View FIGURE 2 ) with 3 pairs of spines, intermediate spines longest, lateral and intermediate spines simple, submedian spines plumose.

Ophthalmic somite with interocular process obsolete ( Fig. 2C View FIGURE 2 ). Eye ( Fig. 2A View FIGURE 2 ) with large, globular cornea, with minute accessory pigment spot; stalk slightly longer than maximum corneal diameter.

Fourth thoracic sternite without finger-like median process.

Antennular peduncle ( Fig. 2F View FIGURE 2 ) reaching level of distal blade of scaphocerite. Proximal segment longer than distal two segments combined; distolateral margin produced, rounded, slightly overreaching midlength of intermediate segment, with row of plumose setae; lateral margin straight, terminating distally in small acute tooth; ventromesial margin armed with small acute tooth; stylocerite short, tapering to acute tip, reaching proximal third of proximal segment (distolateral lobe excluded); statocyst well developed, rounded. Intermediate segment slender, about half of length of proximal segment, marginally with long plumose setae. Distal segment slender, non-setose, obliquely articulated with flagella. Upper flagellum biramous, proximal 9 segments fused, shorter free ramus consisting of 10 segments; groups of long aesthetascs present on proximal fused rami and shorter free ramus.

Antenna with stout basicerite ( Fig. 2G View FIGURE 2 ) armed ventrolaterally with acute tooth, dorsal margin with proximal angular process. Scaphocerite well developed, 2.7–3.3 times as long as maximum broad, lateral margin almost straight, terminating in acute tooth falling distinctly short of distal margin of subquadrate lamella; carpocerite falling slightly short of midlength of scaphocerite.

Epistome unarmed.

Mandible ( Fig. 3A View FIGURE 3 ) moderately slender, without palp; molar process obliquely truncate distally, with blunt teeth and few short setae; incisor process obliquely truncate distally, with three acute distal teeth. Maxillula ( Fig. 3B View FIGURE 3 ) with feebly bilobed palp; upper lacinia broad, distal margin truncate, with 7 simple spines, interspaced with long setae, ventral margin with 2 long setae; lower lacinia narrower than upper lacinia, with some long slender spines distally and numerous shorter setae. Maxilla ( Fig. 3C View FIGURE 3 ) with simple palp tapering distally; distal endite deeply bilobed, terminally with dense long setae, upper lobe broader than lower lobe, lower lobe rounded distally; proximal endite obsolete; scaphognathite well developed, with dense plumose setae marginally, anterior lobe tapering slightly distally, rounded, posterior lobe distally subquadrate. First maxilliped ( Fig. 3D View FIGURE 3 ) with slender palp; distal endite broad, mesial margin densely setose, proximal endite obsolete; exopod with flagellum well developed, terminally with 4 or 5 long setae, caridean lobe well developed; epipod robust, triangular, feebly bilobed. Second maxilliped ( Fig. 3E View FIGURE 3 ) with normal endopod; ischium and basis feebly demarcated, obliquely articulated with merus, mesial surface slightly concave; merus elongate, about twice as long as carpus; carpus short, with anterolateral margin bluntly pointed; propodus with anteromesial margin produced, broad, with sparse setae; dactylus moderately broad, mesial margin almost straight, with marginal dense setae and row of sparse submarginal setae; exopod with well developed flagellum, terminally with long setae; epipod subquadrate, broad, without podobranch. Third maxilliped ( Fig. 3F View FIGURE 3 ) with endopod reaching level of proximal fourth of scaphocerite; coxal plate well developed, oval; antepenultimate segment twisted, with long ventral setae and a single short distodorsal seta, weakly demarcated from basis; penultimate segment 1.4–1.6 times as long as ultimate segment, ventral surface long setae; ultimate segment tapering distally, with set of transverse rows of short plumose setae; exopod with well developed flagellum, distally and distomesially with 4–7 long setae; small arthrobranch present.

Branchial formula shown as Table 1.

First pereiopod ( Fig. 4A View FIGURE 4 ) slender, overreaching distal margin of scaphocerite by lengths of distal half of palm and dactylus. Merus slightly longer than carpus, unarmed. Carpus subequal to chela in length, slightly widened distally, with longitudinal row of long grooming setae distoventrally. Chela ( Fig. 4B View FIGURE 4 ) 0.4–0.5 times as long as carapace, palm subcylindrical, slightly compressed, with 5 transverse rows of short, serrulate grooming setae proximoventrally; fingers 1.2–1.4 times as long as palm, each terminating in small, hooked unguis, cutting borders situated laterally, unarmed.

Second pereiopods ( Fig. 4C View FIGURE 4 ) well developed, similar, overreaching distal margin of scaphocerite by distal part of carpi and chelae. Merus slender, entire, subequal to carpus in length. Carpus slender, entire, 0.6 times as long as carapace, 1.2–1.5 times as long as palm, slightly widening distally. Chela slightly bowed, 0.8–0.9 times as long as carapace, 1.4–1.5 times as long as carpus; palm 1.0–1.3 times as long as dactylus, slightly compressed; dactylus ( Fig. 4D View FIGURE 4 ) terminating in hooked, acutely pointed unguis, cutting border situated laterally, armed proximally with 1–3 small, acute, recurved teeth, remaining part entire, sharply edged; fixed finger ( Fig. 4D View FIGURE 4 ) generally similar to dactylus, armed proximally with 3 small, acute, recurved teeth.

Ambulatory pereiopods increasing in length posteriorly. Third pereiopod ( Fig. 4E View FIGURE 4 ) slender, falling slightly short of level of distal margin of scaphocerite. Merus 2.4–2.6 times as long as carpus, unarmed. Carpus unarmed, distodorsal angle prominent. Propodus 2.2–2.6 times as long as carpus, armed with pair of long distoventral spines and set of 5 spaced spines on ventral margin, distodorsally with long spiniform setae. Dactylus ( Fig. 4F View FIGURE 4 ) slightly compressed, dorsal margin weakly bowed, ventral margin with 1 subterminal accessory tooth, unguis not clearly demarcated. Fourth pereiopod similar to third, falling slightly short of level of distal margin of scaphocerite. Fifth pereiopod overreaching level of distal margin of scaphocerite by length of dactylus. Carpus 1.2 times as long as that of third pereiopod. Propodus ( Fig. 4G View FIGURE 4 ) with ventral margin with 1 distoventral and 2 subterminal spines and tufts of setae and spaced set of 2 spines proximal to distal group of spines.

Male first pleopod ( Fig. 4H View FIGURE 4 ) with endopod ( Fig. 4I View FIGURE 4 ) short, reaching level of proximal third of exopod, generally oval, distally expanded, prominent short appendix interna arising at distal two-fifth of mesial margin, fringed with sparse simple setae distally, long plumose setae proximomesially. Endopod of male second pleopod ( Fig. 4J View FIGURE 4 ) with appendices interna and masculina arising at proximal two-fifths of mesial margin; appendix interna slender, slightly overreaching tip of appendix masculina, with few distal cincinnuli; appendix masculina with 2 long spiniform setae terminally, 5 setae laterally.

Uropod ( Fig. 2D View FIGURE 2 ) with protopodite posteroventrally produced; exopod broad, overreaching posterior margin of telson, posterior margin broadly rounded, lateral margin nearly straight, terminating in small acute tooth, with larger mobile spine just mesial to distolateral tooth; endopod reaching distal margin of exopod, slightly tapering distally.

Description of ovigerous female. Meristic characters similar to, but general body form more robust than those of male and small female. Rostrum distinctly arched ( Fig. 5A View FIGURE 5 ). Second pereiopod with carpus slightly shorter than palm ( Fig. 5B View FIGURE 5 ); cutting borders of fingers armed with more acute teeth ( Fig. 5C View FIGURE 5 ).

Coloration. See Figure 6A, B View FIGURE 6 . Body and appendages generally transparent. Lateral and posterodorsal part of carapace with sparse yellow spots. Transverse, narrow white band running across posterior part of carapace. Posterior half of subcarinate part of third abdominal tergum with large white patch anteriorly tapering, extending obliquely ventrally, posterior margin of patch fringed with short red stripe; midlength of dorsal midline with distinct yellow spot outlined in red on either side. Pleura of first to fifth abdominal somites with yellow or white spots at base of pleopods. Posterior margin of sixth somite with transverse red stripe. Telson transparent, midlength with broad, white transverse band, posterior margin white. Eyestalk white, anterodorsally with longitudinal purple stripe. First and second pereiopods with meri proximally transparent, subterminally white, terminally purple, continuing posterior part of carpi. Midlength of carpi white, terminally purple, extending to proximal part of palms. Fingers largely purple, tips white, palms largely white. Proximal half of uropods transparent, posterior half white, with large, purple rounded patch on distal part of exopods.

Etymology. The specific epithet, luteomaculatus is coined from the Latin luteus meaning yellow and macula meaning a spot, in allusion to the beautiful golden-yellow spots scattered on the carapace and abdomen.

Common name. Tsukihoshi-kakure-ebi (new Japanese name).

Distribution. Kume-jima Island, Ryukyu Islands, Japan; Batangas Bay, Luzon, Philippines, East Kalimantan, Indonesia, and Milne Bay, New Guinea Island, Papua New Guinea.

Bathymetric range. Sublittoral zone, to 32 m.

Host. Pachycerianthus sp. ( Anthozoa: Ceriantharia: Cerianthidae ). Underwater observation at Kume-jima Island by one of us (JO) represented that specimens of the new species lived on the basal tube of the cerianthid.

Remarks. The colour pattern in life of A. luteomaculatus sp. nov., most notably the presence of distinct yellow spots on the carapace and abdomen, is unlike any previously reported congeneric species.

Morphologically, the obsolete interocular process at the ophthalmic somite and armature of the rostrum link A. luteomaculatus sp. nov. to A. magnificus comb. nov., also known from Western Pacific region. We compared the specimens of the present new species with those of A. magnificus comb. nov. listed under “Material examined” of that species. The present new species is distinguishable from A. magnificus comb. nov. by the distinctly elevated and subcarinate posterior median carina of the third abdominal tergum, and the narrow scaphocerite being 2.7–3.3 times as long as broad, instead of 1.9–2.4 times in A. magnificus comb. nov.

The holotype and three paratypes from the Ryukyu Islands were collected during a survey to prepare the decapod crustacean Kume-jima Island guidebook by Kawamoto & Okuno (2003). The new species was briefly reported in the book as Periclimenes sp. D . The species reported as Periclimenes cf. venustus from Papua New Guinea ( Debelius 1999) and as Periclimenes sp. from East Kalimantan, Indonesia ( Fransen 2004) are also identifiable without doubt with A. luteomaculatus sp. nov. on account of its distinctive colour pattern in life.