Clorida seversi Moosa 1973

Clorida seversi Moosa, 1973

[New Japanese name: Minami-meboso-shako]

(Figs. 7, 8)

Clorida seversi Moosa, 1973: 22–24, fig. 4 [type locality: north of Du Rowa Islands, north of Nuhu Rowa, Kai, Indonesia, 5°32'S, 132°41'E, 27–37 m].— Makarov 1979: 54, 55.— Ahyong 2001: 226–228, fig. 111.

Material examined. All specimens were collected using a yabby pump. RUMF-ZC-7447, 1 male (TL 35.6 mm, CL 6.1 mm), 1 female (TL 30.5 mm, CL 5.2 mm), southwest of Hatoma Island, adjacent to Iriomote Island, Ryukyu Islands, 24°27'59"N, 123°48'32"E, 18 m, sandy-muddy substate, coll. H. Nakajima, 14 Jun. 2022. RUMF-ZC-7448, 1 male (TL 49.7 mm, CL 8.6 mm), same locality data as in RUMF-ZC-7447, coll. T. Sato. RUMF-ZC-7449, 1 female (TL 17.8 mm, CL 3.0 mm), Indabishi, Iriomote Island, 24°25'06"N, 123°50'09"E, 17.6 m, sandy bottom, coll. H. Nakajima, 12 Sep. 2022.

Diagnosis. Carapace with anterolateral spines (Fig. 7A). A1 somite dorsal processes distally acute (Fig. 7B). Distal margin of second segment of A2 peduncle extending anteriorly beyond eyes (Fig. 7A). Mandibular palp absent. Raptorial claw dactylus with 4 well-formed teeth (Fig. 7E); extensor margin without basal notch. TS5 lateral process with short triangular lobe (Fig. 7C, D). AS 1–5 without SM carinae. Postanal carina present (Fig. 7G). Eye stalk with black band dorsolaterally (Fig. 7A, B). A2 scale not entirely black (Fig. 7A).

Colour in life. Body entirely beige, with scattered small black spots (Fig. 8). TS6–8 and AS 1–6 posterior margins with (Fig. 8C, D) or without (Fig. 8A) narrow black lines. AS 1–5 with white patches marginally (Fig. 8D). Uropodal endopod with small black spots; posterior margin of proximal segment and mesial half of distal segment with dense black spots. Mature female (Fig. 7C, D, RUMF-ZC-7447, TL 30.5 mm) with developed orange ovaries visible externally.

Remarks. Clorida seversi can be distinguished from the other congeners by the following characters (see Ahyong 2001): raptorial claw dactylus with four well-developed teeth (Fig. 7E); mandibular palp absent; lateral process of TS5 short, triangular lobe (Fig. 7C, D); and postanal carina present (Fig. 7G). Our specimens examined have all the diagnostic characters of C. seversi and there are no distinct differences from a re-description of the species by Ahyong (2001).

This is the first record of the species from Japanese waters. The largest male specimen examined (RUMF-ZC-7448, TL 49.7 mm), which also represents the largest specimen of C. seversi hitherto reported, is now designated as the standard specimen for the new Japanese name (Minami-meboso-shako) proposed here.

Distribution. Indonesia, Vietnam, northeastern Australia (Ahyong 2001), and now Japan. In Japan, only known from Hatoma Island and Iriomte Island, Ryukyu Islands, southwestern Japan (Fig. 11).

Ecological note. Soft substrates in coral reef lagoons, 9–15 m depth (Ahyong 2001). The holotype was collected about 27–37 m depths (15–20 fathom; Moosa 1973). In this study, all the specimens were collected from fine sand and mud sediments covered by Halophila ovalis and ghost shrimp mounds in inner reefs, about 20 m depth (Fig. 8E). Makarov (1979) reported this species from 110 m depth in Vietnam.