Trachysalambria albicoma ( Hayashi & Toriyama, 1980 )

Chan, Tin-Yam, Cleva, Régis & Chu, Ka Hou, 2016, On the genus Trachysalambria Burkenroad, 1934 (Crustacea, Decapoda, Penaeidae), with descriptions of three new species, Zootaxa 4150 (3), pp. 201-254 : 240-241

Trachysalambria albicoma ( Hayashi & Toriyama, 1980)

( Figs. 16 , 20 E)

Trachypenaeus albicomus Hayashi & Toriyama, 1980: 69 , figs. 1, 2a [type locality: Tosa Bay, Japan]; Hayashi, 1986: 75, fig. 35; 1992: 141, figs. 75a,76a, 77a, 78a; Dall & Rothlisberg, 1990: 104.

Trachysalambria albicoma .— Pèrez Farfante & Kensley, 1997: 149; Sakaji & Hayashi, 2003: 147, fig. 2; De Grave & Fransen, 2011: 228.

Material examined. Japan. Tosa Bay: 15 m, 18.03.2008, 2 females cl 17.2 and 17.7 mm ( NTOU M01999 ) ; 25 m, 4 males cl 14.0–16.0 mm, 3 females cl 18.7–21.0 mm (MNHN IU-2014-7037), 1 female cl 22.2 mm (MNHN IU- 2014-7038); 35 m, 4 males cl 16.5–18.5 mm, 6 females cl 23.5–27.0 mm (MNHN IU-2014-7042). Kochi Prefecture: Mimase Fish market, 0 6.12.1977, 2 males cl 13.0 and 14.0 mm, 2 females cl 17.2 and 17.8 mm ( MNHN IU- 2014-7041 ) ; 0 8.06.1980, 2 females cl 22.6 and 24.6 mm (MNHN IU-2014-7040, ex NFU); 20–40 m, 0 8.06.1990, 2 males cl 13.6 and 14.6 mm, 1 female cl 24.0 mm (MNHN IU-2014-7039, ex NFU).

Taiwan. Dasi fishing port, Yilan County: 17.07.1984, 2 females cl 15.0 and 16.1 mm ( NTOU M02000 ) ; 0 7.07.1985, 1 female cl 17.7 mm (NTOU M02001 ). Budai fishing port, Chiayi County: 26.05.1985, 5 females cl 14.0– 15.6 mm ( MNHN IU- 2014-7036 ) ; 20.01.1995, 58 males cl 16.9–22.3 mm, 17 females cl 12.9–16.9 mm (NTOU M02002 ). Kaohsiung County, no date, 1 male cl 16.3 mm, 1 females cl 15.1 mm ( NTOU M02003 ) . Donggang fishing port, Pingtung County: 29.10.1988, 1 male cl 13.7 mm ( NTOU M02004 ) ; 21.10.1995, 1 male cl 10.5 mm (NTOU M02005 ); 12.02.2000, 4 females cl 21.2–22.8 mm (NTOU M02006 ), 3 females cl 20.5–22.5 mm (NTOU M02007 ); 15.12.2007, 1 female cl 18.8 mm (NTOU M02009 ); 14.08.2015, 1 female cl 18.2 mm (NTOU M02008 ). No specific locality: 1 male cl 13.5 mm, 1 female cl 16.9 mm ( NTOU M02010 ) ; 5 males cl 10.0– 12.7 mm, 18 females cl 10.7–17.9 mm (NTOU M02011 ); 1 female cl 17.2 mm (NTOU M02012 ).

Description. Carapace pubescent but abdomen less pubescent and sometimes even nearly naked. Rostrum with 6–9 (usually 7 or 8, excluding epigastric tooth) dorsal teeth that generally distributed rather evenly along dorsal border but occasionally unarmed near tip; slightly to distinctly curved upwards in females, tip not recurved downwards, ventral border straight to convex but ventral margin of tip always straight, tips of rostral teeth aligned in straight or concave configuration; in males rostrum rather horizontal straight, tip not recurved downwards, ventral border straight to convex, tips of rostral teeth more or less aligned in a straight line; generally extending to about tip of second segment of antennular peduncle; postrostral carina low and only extending to about middle of carapace. Pereiopods I to III with well-developed epipods. Pereiopod I with ischial spine minute or absent. Pereiopod IV in females with coxa not medially expanded. Pereiopod V reaching middle to tip of scaphocerite (generally longer in small individuals). Abdomen with low dorsal carinae on somites II to VI; that on somite II short, almost leveled, sometimes even indistinct; somite III only with dorsal carina at posterior 2/3 of somite; ridges on somites IV and V posteriorly incised and not terminating in spines. Telson with blunt dorsolateral carinae, bearing 3 or 4 pairs of movable lateral spines. Male petasma with lateral margins of stem distinctly converging distally; distolateral lobes with ventral margins more or less straight, tips of dorsal and ventral flaps coinciding, forming sharp angle. Female thelycum with anterior plate semi-triangular, generally sunken or flattened; anterior margin of posterior plate distinctly concave, with median cleft.

Coloration. Body greyish pink, darker dorsally and paler laterally. Rostrum greyish brown to dark grey with tip plate white. Eyes black-brown. Antennular and antennal flagella whitish to pale white. Pereiopods pale white with pale pink patches. Pleopods pale brown with lateral surfaces bearing white patches. Uropods reddish brown distally and pinkish brown basally, outer margin of exopod and inner margin of endopod whitish.

Distribution. Northwestern Pacific; known with certainty only from Japan and Taiwan; at depths of 10– 40 m.

Remarks. Trachysalambria albicoma generally has less pubscence and weaker carinae on the body. The abdomen is sometimes nearly naked (more often in small individuals) in this species. Other species of Trachysalambria except T. brevisuturae have both the carapace and abdomen distinctly pubescent. The dorsal carina on the abdomen in T. albicoma is generally lowest amongst the Indo-West Pacific species of the genus, with that on the somite II almost leveled or indistinct ( Fig. 16 C). Nevertheless, the eastern Pacific species T. brevisuturae is even less pubescent (even carapace sparsely pubescent) and ridged (both abdominal somites II and III lacking dorsal carinae) than T. albicoma .

The less ridged body of T. albicoma shows some resemblance with T. starobogatovi on the other side of the Indo-West Pacific. Nevertheless, the two species can be readily separated from each other by the characters discussed under the “Remarks” of the latter species. There are also significant genetic differences between the two species (>7% sequence divergence in 12S and 16S rRNA genes, Tables 2, 3). Like T. starobogatovi , T. albicoma appears to have a rather restricted distribution. At present T. albicoma is only confirmed to occur in Japan and Taiwan. The report of this species from Gulf of Thailand still needs to be confirmed as the photograph provided by Chitiamvong & Supongpan (1992: pl. 48) is too unclear. Sakaji & Hayashi (2003) considered that the Queensland specimens reported by Schmitt (1926) as “ T. curvirostris ” may actually refer to the present species because Schmitt’s (1926) material has a short postrostral carina, longer pereiopods and 7 dorsal rostral teeth. However, as shown in the present work, these three characters alone are not enough for positive identification of the species in this genus. Re-examination of Schmitt’s (1926) Australian specimens is necessary to determine their exact identities. Sakaji & Hayashi (2003) also referred the “ T. curvirostris ” photograph of Yu & Chan (1986: 170, unumbered photograph) of a Taiwanese specimen with “shinier (= shiner) carapace” to T. albicoma . The specimen for this photograph could not be located for the present study, but the photograph clearly shows the antennal flagella being reddish brown and not the typical whitish color of the present species. Thus, it is highly likely that the photograph of Yu & Chan (1988) belongs to the greyish form of T. curvirostris instead of T. albicoma .

Figures

FIGURE 16. Trachysalambria albicoma (Hayashi & Toriyama, 1980), Kochi Prefecture, Japan: A, C, G, H, female cl 24.6 mm (MNHN IU- 2014 - 7040); B, D – F, male cl 14.6 mm (MNHN IU- 2014 - 7039). A, cephalothorax, lateral view; B, rostrum, lateral view; C, dorsal part of abdominal somites II to VI, lateral view; D – F, petasma, ventral, dorsal and upper views, respectively; G, thelycum, ventral view; H, telson, dorsal view.

FIGURE 20. A, Trachysalambria aspera (Alcock, 1905), Donggang fishing port, Pingtung County, Taiwan, male cl 18.2 mm (MNHN IU- 2014 - 6971); B, T. aspera, Madagascar, ATIMO VATAE, stn CP 3570, male cl 17.0 mm (MNHN IU- 2014 - 8772); C, T. curvirostris (Stimpson, 1860), Magong fishing port, Penghu County, Taiwan, female cl 23.3 mm (NTOU M 02020); D, T. curvirostris, Dasi fishing port, Yilan County, Taiwan, female cl 25.9 mm (NTOU M 01952); E, T. albicoma (Hayashi & Toriyama, 1980), Donggang fishing port, Pingtung County, Taiwan, female cl 18.2 mm (NTOU M 02008); F, T. starobogatovi (Ivanov & Hassan, 1976), ATIMO VATAE, stn TP 19, male cl 14.4 mm (MNHN IU- 2014 - 8774).