Leptalpheus denticulatus, Anker & Marin, 2009
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https://doi.org/ 10.5281/zenodo.5341630 |
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persistent identifier |
https://treatment.plazi.org/id/03AAE925-9F1E-FFE0-FF7E-F85168F54F55 |
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treatment provided by |
Diego |
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scientific name |
Leptalpheus denticulatus |
| status |
sp. nov. |
Leptalpheus denticulatus View in CoL , new species
( Figs. 1–6 View Fig View Fig View Fig View Fig View Fig View Fig , 7a, b View Fig , 8 View Fig )
Leptalpheus cf. pacificus View in CoL B – Anker et al, 2006: Table 1. Leptalpheus cf. pacificus View in CoL C – Anker et al, 2006: Table 1. Type material. – Vietnam: Holotype: male, CL 6.4, TL 19.1 (MNHN-Na 17064), Nhatrang Bay, Dam Bay, intertidal sand flat, fringe mangrove, bait suction pump, from burrow of Glypturus cf. armatus, coll. I. Marin, 17 Jun.2004. Paratypes: 1 female, CL 7.6, TL 23.8 (FLMNH UF Arthropoda 15018), same collection data as for holotype; 1 female, CL 10.0, TL not measured (USNM 1110002), same collection data as for holotype [specimen dissected]; 1 breeding female, CL 14.5, TL 44.7 (MNHN-Na 17065), same collection data as for holotype [specimen photographed].
Additional (non-type) material. – Fiji: 1 female, CL 6.0, TL 18.8 ( LACM CR 2005 View Materials - 006.1 View Materials ), Viti Levu , Yaqara Bay, ca. 2 km north of Yaqara Pastoral Community, sand beach fringed with mangrove, bait suction pump, from burrow, depth: 1.0– 1.5 m, coll. A. Anker & T. Faught, 10 Jan.2005 [fcn 845; specimen photographed] ; 1 male, CL 6.7, TL not measured ( LACM CR 2005 View Materials - 007.1 View Materials ), Viti Levu , Yaqara Bay , ca. 2 km north of Yaqara Pastoral Community, Nasilau Point, sand beach, bait suction pump, from burrow, depth 0.5–1.0 m, coll. A. Anker & A. Bunouf, 27 Jan.2005 [fcn 594; specimen photographed, dissected] ; 1 male, CL 7.4, TL 19.5 (MNHN-Na 15776), same collection data as for previous specimen [fcn 562; specimen photographed] ; 1 female, CL 5.3, TL 16.7 ( OUMNH-ZC 2005-07-16), same collection data as for previous specimen [fcn 574] . Philippines: 1 male, CL 6.2, TL 16.8 ( ZRC 2005.0086 View Materials ), Panglao Island , Alona Beach, Sta. M1, 9°32.9’N 123°46.6’E, intertidal and shallow subtidal, depth 0–1 m, bait suction pump, from burrow of Neocallichirus calmani , coll. P. C. Dworschak, 3 Jun.2004 [fcn PD-1; specimen photographed] GoogleMaps ; 1 female, CL 6.5, TL 17.65 ( ZRC 2005.0087 View Materials ), same collection data as for previous specimen [fcn PD-1] GoogleMaps .
Comparative material. – Leptalpheus pacificus . Hawaii: 1 breeding female, CL 8.1, TL not measured ( FLMNH UF Arthropoda 12473), Maui , Hekili Point, 20°8108’ N 156° 6214’E, back reef 0–1 m, hand collected, C. Pittman, 28 Sep.2007 ; 1 breeding female, CL and TL not measured ( USNM 205907 View Materials ), Oahu , Honolulu, Waikiki Beach, coll. R. Heard, 7 Jan.1988 .
Description. – (based on Nhatrang specimens) – Body moderately slender, rather stout in large individuals, carapace and abdomen very slightly compressed laterally, glabrous except for minute pits ( Fig. 1a View Fig ). Carapace with inconspicuous suture proximal to base of antenna ( Fig. 1b View Fig ). Frontal margin protruding and broadly rounded, without rostral projection or orbital teeth, without orbital crests ( Fig. 1a View Fig ). Pterygostomial angle rounded ( Fig. 1b, c View Fig ); branchiostegial region with pronounced “lip” anteriorly ( Figs. 1b, c View Fig ); cardiac notch deep ( Fig. 1d View Fig ). Eyes not visible in dorsal view, anterior portion visible in lateral view ( Fig. 1a–c View Fig ); anteromesial process well marked; cornea small, lateral, pigmented ( Fig. 1c, e View Fig ). Ocellar beak not conspicuous.
Antennular peduncle relatively stout ( Fig. 1a View Fig ), flattened dorsoventrally; second segment about twice as long as broad, about as long as dorsally visible portion of first segment; stylocerite not reaching distal margin of first segment, subacute distally ( Fig. 1a, b View Fig ); ventromesial carina of first segment with strong tooth ( Fig. 1f View Fig ); lateral flagellum biramous, with shorter ramus well developed, situated at third segment ( Fig. 1g View Fig ). Antenna with basicerite bearing strong ventrolateral tooth ( Fig. 1b View Fig ); scaphocerite broadly ovate, anterior margin of blade slightly convex, but not protruding beyond distolateral tooth ( Fig. 1a View Fig ); carpocerite long, stout, reaching far beyond scaphocerite ( Fig. 1b View Fig ).
Mouthparts and third maxilliped typical for genus ( Fig. 2a–f View Fig ). Mandible with incisor process bearing six teeth, median two largest ( Fig. 2a View Fig ). Maxillule with bilobed palp, both lobes with one stiff seta ( Fig. 2c View Fig ). First maxilliped with expanded caridean lobe on exopod ( Fig. 2e View Fig ). Second maxilliped with elongate epipod ( Fig. 2f View Fig ). Third maxilliped relatively slender, elongate; lateral plate acutely produced ( Fig. 2g View Fig ); ultimate segment with rows of long, distally thickened setae, tip unarmed; arthrobranch very large ( Fig. 2g View Fig ).
Chelipeds strongly asymmetrical in shape, unequal in size ( Fig. 3 View Fig ), carried folded when not in use ( Fig. 8a View Fig ). Major cheliped (on either left or right side) enlarged, elongate ( Fig. 3a, b View Fig ); ischium short, ventromesial margin without subtriangular tooth ( Fig. 3b View Fig ); merus long, slender, with smooth margins, distally not widening, ventrally depressed, distal margin ending bluntly; carpus short, cup-shaped, with blunt distolateral process; chela subcylindrical, palm smooth, ventromesially excavated, about three times as long as high; adhesive discs well developed ( Fig. 3a, c View Fig ); fingers about 1/3 length of palm; dactylus moderately curved distally, with subacute tip, cutting edge with one feebly protruding, distally rounded, median tooth, about 1/3 as high as long and small, subtriangular, proximal tooth; pollex as long as dactylus, abruptly ending, tip truncate, with two subacute teeth, cutting edge with one much larger subtriangular proximal tooth and one smaller truncate distal tooth ( Fig. 3c, d View Fig ). Minor cheliped weaker than major cheliped, slender ( Fig. 3e View Fig ), ischium short, unarmed; merus slender, ventrally depressed ( Fig. 3e View Fig ); carpus short, cup-shaped; chela smooth, subcylindrical, with fingers about as long as palm, tips crossing when chela closed; cutting edges of dactylus and pollex with small curved teeth proximally and two larger opposing teeth at about 2/3 of finger length ( Fig. 3f View Fig ).
Second pereiopod relatively slender ( Fig. 2h View Fig ); ischium about 3/4 length of merus; carpus five-segmented, segments with ratio approximately equal to 3.5/1/1.5/1/2.5; chela simple, slightly shorter than first carpal segment; fingers as long as palm. Third pereiopod moderately slender ( Fig. 3i View Fig ), ischium unarmed; merus flattened mesially, about 2.5 times as long as ischium, about four times as long as wide, with convex dorsal and ventral margins ( Fig. 2i View Fig ); carpus less than 1/2 length of merus, with distoventral spiniform seta; propodus longer than carpus, with two ventral spiniform setae and one distoventral spiniform seta proximal to dactylus; dactylus simple, conical, about 2/5 length of propodus, curved ( Fig. 2j View Fig ). Fourth pereiopod generally similar to third. Fifth pereiopod much more slender than third and fourth pereiopods ( Fig. 2k View Fig ); ischium and merus not flattened mesially, unarmed; carpus without distal spiniform seta; propodus as long as merus, without spiniform setae, distally with at least six rows of setae; dactylus similar to that of third and fourth pereiopods.
First to fifth pleomeres with minute pits on surface; posteroventral angles rounded; sixth pleonite with large articulated plate posteroventrally, dividing suture appearing somewhat incomplete ( Fig. 1l View Fig ). Male second pleopod ( Fig. 2l View Fig ) with appendix interna and appendix masculina, latter about
1.5 times as long as former and bearing several slender, spiniform, apical and subapical setae ( Fig. 2m View Fig ).
Uropod with lateral lobe of protopod bearing two small subacute teeth distally ( Fig. 1h View Fig ); endopod somewhat longer than exopod, without specific features; exopod with truncate posterior margin and with feebly protruding, blunt distolateral tooth adjacent to robust distolateral spiniform seta; lateral half of diaeresis mostly straight except for central-most portion curved into small tooth ( Fig. 1i View Fig ); mesial portion deeply incised forming stout subtriangular tooth proximal to mesial margin ( Fig. 1i View Fig ).
Telson moderately slender, slightly tapering distally, about 2.5 times as long as wide proximally ( Fig. 1j View Fig ); dorsal surface pitted ( Fig. 1k View Fig ), with two pairs of strong spiniform setae inserted at short distance from lateral margin, at about 1/3 and 3/5 length of telson, respectively ( Fig. 1j View Fig ); posterior margin broadly rounded, each posterolateral angle with two spiniform setae, mesial at least five times longer than lateral ( Fig. 1k View Fig ); anal tubercles small, feebly sclerotised.
Gill/exopod formula typical for genus: 5 pleurobranchs (above P1–5); 1 arthrobranch (above Mxp3); 0 podobranch; 2 lobe-shaped epipods (Mxp1–2); 5 mastigobranchs or straplike epipods (Mxp3, P1–4); 5 sets of setobranchs (P1–5); 3 exopods (Mxp1–3).
Colour pattern. – Semitransparent with more or less pronounced pinkish tinge; carapace dorsally with reddish chromatophores; each pleonite with diffuse transverse band of reddish chromatophores along posterior margin; antennular and antennal peduncles, telson and uropod more intense pink due to higher concentration of reddish chromatophores; walking legs and antennular and antennal flagella semitransparent; major chela hyaline-whitish with scattered reddish chromatopores ( Fig. 8 View Fig ).
Size. – The smallest examined specimen is a female from Fiji with 5.3 mm CL and 16.7 mm TL; the largest is an ovigerous paratype female from Nhatrang with 14.5 mm CL and 44.7 mm TL. The diameter of embryos (measured in the largest female from Nhatrang) is approximately 0.6 × 0.5 mm.
Etymology. – The specific name ( denticulatus – Latin for “bearing a denticle or small tooth”) refers to the presence of a small tooth on the central portion of the uropodal diaeresis, a key feature to distinguish the new species from the closely related L. pacificus (see under Remarks below).
Type locality. – Nhatrang Bay , Vietnam .
Distribution. – Western tropical Pacific; presently known from three distant localities: Nhatrang Bay in Vietnam (type locality); Viti Levu in Fiji; and Panglao Island, southwest of Bohol, in the Philippine Archipelago.
Ecology. – All specimens were collected from burrows of large callianassid ghostshrimps on intertidal or shallow subtidal sand flats, fringed by mangroves. In Nhatrang, most specimens were collected from burrows of Glypturus cf. armatus (A. Milne-Edwards, 1870) [IM, pers. obs.], whereas the two Panglao specimens were collected from burrows of Neocallichirus calmani ( Nobili, 1904) [field notes by P. C. Dworschak]. None of the Fijian specimens was collected together with a host, but one specimen of Neocallichirus sp. was collected at the same locality and the presence of typical mounds of Glypturus sp. was also noted [AA, pers. obs.].
Remarks. – Leptalpheus denticulatus , new species, is closely related to L. pacificus . These two species share a great number of characters, e.g., they have a very similar frontal margin of the carapace and a nearly identical dentition on the major chela. However, L. denticulatus , new species, can be separated from L. pacificus by the presence of a small tooth on the central portion of the uropodal diaeresis, just before the diaereis slopes abruptly into the large mesial incision ( Figs. 1i View Fig , 5o View Fig ), and the slightly more slender second pereiopod, with a smaller chela and shorter first carpal segment (cf. Figs 2h View Fig , 6g View Fig and Fig. 7f View Fig ). The figures of L. pacificus in Banner & Banner (1974) must be used with some caution for they appear to be slightly inaccurate. For instance, the stylocerite was illustrated with tip overreaching the distal margin of the first segment of the antennular peduncle (see Banner & Banner, 1974: Fig. 1A View Fig ) and the lateral lobe of the uropodal protopod as bluntly rounded ( Banner & Banner, 1974: fig. 1M). However, examination of these two features in L. pacificus (FLMNH UF12473) shows that the stylocerite actually falls short of the distal margin of the first segment ( Fig. 7e View Fig ), while the lateral lobe of the uropodal protopod bears two broadly rounded teeth or lobes ( Fig. 7g, h View Fig ), although the latter appear to be blunter than the more distinctly protruding, subacute teeth of L. denticulatus , new species (compare with Figs. 1h View Fig , 5n View Fig ). More specimens of L. denticulatus , new species, and L. pacificus must be examined in order to conclude whether the configuration of the lateral lobe of the protopod (blunt vs. subacute teeth) can be reliably used to distinguish these two species.
Some intraspecific variation was observed among specimens of L. denticulatus , new species, either from the same or from different localities. For instance, the Nhatrang specimens ( Figs. 1–4 View Fig View Fig View Fig View Fig ) differ from the Fijian specimens ( Figs. 5–6 View Fig View Fig ) by the proportions of the third pereiopod, particularly in the merus being somewhat broader and having more convex margins (cf. Figs. 2i View Fig , 6h View Fig ). The two illustrated Nhatrang paratypes, a 10 mm CL female and a 14.5 mm CL breeding female, differ from each other by the extension of the blunt tooth on the cutting edge of the major chela dactylus, which is relatively short and more protruding in the smaller female ( Fig. 3c View Fig ), and distinctly longer and more flattened in the large female ( Fig. 4b View Fig ); this latter configuration is similar to that of the Fijian specimens ( Fig. 6b, c View Fig ) and especially to the Hawaiian L. pacificus ( Fig. 7c, d View Fig ). They also differ by the ratio of the fingers to the palm, which is closer to 1/ 3 in the smaller female ( Fig. 3c View Fig ) and almost 1/ 2 in the larger female ( Fig. 4a View Fig ), approaching the ratio observed in L. pacificus ( Fig. 7c, d View Fig ). These differences are possibly due to the age-related allometry of the major cheliped, but we feel that further studies, involving morphometric studies and DNA sequencing, are needed to elucidate the nature of this variation.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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Leptalpheus denticulatus
| Anker, Arthur & Marin, Ivan N. 2009 |
Glypturus
| Stimpson 1866 |