Leptalpheus dworschaki, Anker & Marin, 2009

Anker, Arthur & Marin, Ivan N., 2009, The Alpheid Shrimp Genus Leptalpheus Williams, 1965, In The Tropical Western Pacific, With Descriptions Of Two New Species (Crustacea: Decapoda: Caridea), Raffles Bulletin of Zoology 57 (1), pp. 91-107 : 100-105

publication ID	https://doi.org/ 10.5281/zenodo.5341630
persistent identifier	https://treatment.plazi.org/id/03AAE925-9F16-FFE7-FC3F-FEB16BC34CB4
treatment provided by	Diego
scientific name	Leptalpheus dworschaki
status	sp. nov.

Treatment

Leptalpheus dworschaki View in CoL , new species

( Figs. 9–12 View Fig View Fig View Fig View Fig )

Leptalpheus sp. 7 aff. pacificus – Anker et al, 2006: Table 1.

Type material. – Philippines: Holotype: male, CL 7.7, TL 21.9 ( NMCR 27540 ), Panglao Island , Sungcolan Bay, Sta. M 11, 9°38.3'N 123°49.6'E, intertidal flat, fringed with mangrove and seagrass, bait suction pump, from burrow of Glypturus sp. , coll. P. C. Dworschak, 7 Jun.2004 [fcn PD-37; specimen dissected] GoogleMaps . Paratype: 1 female, CL 7.7, TL 23.9 ( ZRC 2005.0085 View Materials ), same collection data as for holotype [fcn PD-36] GoogleMaps .

Description. – Body not particularly slender or stout ( Fig. 10a View Fig ), carapace and abdomen slightly compressed laterally, glabrous. Carapace with inconspicuous suture proximal to base of antenna ( Fig. 9b, c View Fig ). Frontal margin protruding and broadly rounded, without rostral projection or orbital teeth, without orbital crests ( Fig. 9a, b, k View Fig ). Pterygostomial angle rounded ( Fig. 9c View Fig ); branchiostegial region with pronounced “lip” anteriorly; cardiac notch fairly deep ( Figs. 9c View Fig , 10a View Fig ). Eyes not visible in dorsal view, anterior portion visible in lateral view ( Fig. 9a, c View Fig ); anteromesial process feebly marked; cornea small, lateral, pigmented. Ocellar beak not conspicuous.

Antennular peduncle relatively stout, 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. 9a, b, k View Fig ); ventromesial carina of first segment with strong tooth ( Fig. 9d View Fig ); lateral flagellum biramous, with shorter ramus well developed, situated at third segment. Antenna with basicerite bearing strong ventrolateral tooth ( Fig. 9b View Fig ); scaphocerite broadly ovate, anterior margin of blade convex but not protruding beyond distolateral tooth ( Fig. 9a View Fig ); carpocerite long, stout, reaching far beyond scaphocerite.

Mouthparts and third maxilliped as in previous species ( Fig. 10b–h View Fig ; for description see above).

Chelipeds strongly asymmetrical in shape, unequal in size ( Figs. 11 View Fig , 12a, b View Fig ), carried folded when not in use ( Fig. 10a View Fig ). Major cheliped (on either left or right side) enlarged, elongate ( Fig. 11 View Fig ); ischium short, ventromesial margin without subtriangular tooth; merus long, slender, with smooth margins, distally not widening, ventrally flattened, distally more depressed, distal margin with blunt lobes; carpus short, cup-shaped, with blunt distal process; chela subcylindrical, palm smooth, ventromesially excavated, about 2.5 times as long as high ( Fig. 11c View Fig ); adhesive discs well developed ( Fig. 11b, c View Fig ); fingers about 1/3 length of palm; dactylus moderately curved distally, with subacute tip, cutting edge with one median subtriangular-rounded tooth, about 1/2 as high as long, without proximal tooth; pollex shorter than dactylus, abruptly ending, with one blunt terminal tooth, cutting edge with two teeth: one much larger subtriangular proximal tooth and one smaller truncate distal tooth ( Fig. 11c, d View Fig ). Minor cheliped shorter and weaker than major cheliped ( Fig. 12a View Fig ); ischium short, unarmed; merus slender, ventrally depressed; carpus very short, cup-shaped; chela smooth, subcylindrical, with fingers about 1.2 times 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 mid-length ( Fig. 12b View Fig ).

Second pereiopod slender; ischium about 3/4 length of merus; carpus five-segmented, segments with ratio approximately equal to: 4/1/1/1/2.5 ( Fig. 12c View Fig ); chela simple, about as long as first carpal segment; fingers as long as palm. Third pereiopod moderately slender ( Fig. 12d View Fig ); ischium unarmed; merus flattened mesially, about 2.5 times as long as ischium, about five times as long as wide; carpus less than 1/2 length of merus, with distoventral spiniform seta; propodus longer than carpus, with three ventral spiniform setae and one distoventral spinifom seta proximal to dactylus; dactylus simple, conical, about 2/5 length of propodus, curved ( Fig. 12d View Fig ). Fourth pereiopod ( Fig. 12e View Fig ) generally similar to third. Fifth pereiopod ( Fig. 12f View Fig ) much more slender than third and fourth pereiopods; ischium and merus not flattened mesially, unarmed; carpus without distal spiniform seta; propodus as long as merus, without spiniform setae, distally with at least seven 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 ( Fig. 10a View Fig ). First pleopod woth very short endopod, latter fringed with setae apically ( Fig. 9f View Fig ). Male second pleopod ( Fig. 9g View Fig ) with appendix interna and appendix masculina, latter almost twice as long as former, and bearing numerous slender, spiniform apical and subapical setae ( Fig. 9h View Fig ).

Uropod with lateral lobe of protopod bearing two small acute teeth distally ( Fig. 9i View Fig ); endopod somewhat longer than exopod, without specific features; exopod with truncate posterior margin and without distinct distolateral tooth adjacent to distolateral spine; lateral portion of diaeresis straight, not curved into tooth centrally; mesial portion deeply incised forming large triangular tooth proximal to mesial margin ( Fig. 9i View Fig ).

Telson moderately slender, more than twice as long as wide proximally ( Fig. 9j View Fig ); dorsal surface pitted, with two pairs of robust spiniform setae inserted at short distance from lateral margin, at about 1/3 and 2/3 length of telson, respectively; posterior margin feebly rounded, posterolateral angles each with pair of spiniform setae, mesial at least four times as long as lateral; anal tubercles small, feebly sclerotised.

Gill/exopod formula as in previous species (see above).

Colour pattern. – Field notes indicated: “Translucent, slightly pink, ovary green”.

Size. – The CL of both specimens is 7.7 mm; the TL ranges from 21.9 mm in the male holotype to 23.9 mm in the female paratype.

Etymology. – The new species is named after Peter C. Dworschak (Naturhistorisches Museum in Wien, Vienna, Austria), the collector of the present specimens, our estimated friend and colleague, and also a well known specialist of the Thalassinidea.

Type locality. – Panglao Island , southwest of Bohol, the Philippines .

Ecology. – Both specimens were collected from a Glypturus cf. armatus burrow, together with gastropods ( Phenacolepadidae ) and sentinel crabs, Macrophthalmus sp. (Ocypodidae) [field notes by P. C. Dworschak].

Distribution. – Western Pacific: presently known only from the type locality in the Philippines.

Remarks. – Leptalpheus dworschaki , new species, is closely related to L. pacificus and the above-described L. denticulatus , new species, but can be separated from both species by the armature on the major chela fingers, in particular by the presence of a distinct blunt tooth on the dactylus (absent in L. pacificus and L. denticulatus , new species, although larger individuals may have a broad bulge at the same position); the absence of a small proximal tooth on the dactylus (present in L. pacificus and L. denticulatus , new species); and the shorter hiatus between the larger proximal and smaller distal teeth on the pollex (this hiatus is almost twice as long in L. pacificus and L. denticulatus , new species) (compare Figs. 11c, d View Fig and Figs. 3c, d View Fig ; 4 b, c View Fig ; 7c, d View Fig ). Leptalpheus dworschaki , new species, can be also separated from L. denticulatus , new species, by the absence of a small tooth on the central portion of the uropodal diaeresis. We were unable to find any other obvious morphological differences between L. dworschaki , new species, and L. pacificus and L. denticulatus , new species.

The length of the second segment of the antennular peduncle and the shape of the frontal margin appear to be somewhat variable in both L. dworschaki , new species ( Fig. 9a, k View Fig ), and L. denticulatus , new species ( Figs. 1a View Fig , 5a View Fig ); the latter species is also variable in the proportions of the merus of the third pereiopod ( Figs. 2i View Fig , 6h View Fig ; see also above). Therefore, these features cannot be reliably used to distinguish L. dworschaki , new species from L. denticulatus , new species, or from L. pacificus .