Clorida rotundicauda ( Miers, 1880 )

Nakajima, Hiroki, Ueda, Tetsuya, Itani, Gyo & Osawa, Masayuki, 2024, The mantis shrimp genus Clorida Eydoux & Souleyet, 1842 (Crustacea: Stomatopoda: Squillidae) in Japan, with the first Japanese record of Cloridina ichneumon (Fabricius, 1798), Zootaxa 5463 (4), pp. 501-523 : 510-514

Clorida rotundicauda ( Miers, 1880)

[New Japanese name: Maruo-meboso-shako]

( Figs. 5 , 6 )

Chloridella rotundicauda Miers, 1880: 15 , pl. 2: figs. 5, 6 [type locality: Formosa (=Taiwan)].— Schmitt 1931: 130–132, pl. 16, figs. 3–5.

Clorida rotundicauda .— Manning 1979: 394–396, fig. 1.— Dong et al. 1983: 84, 85, pl.1. fig. 1— Ahyong 2001: 216, 217.— Ahyong & Naiyanetr 2002: 293.— Ahyong et al. 2008: 87, 88, figs. 66, 67.

Material examined. All specimens are collected from intertidal mud-flats by using yabby pumps. RUMF-ZC-7446, 1 heavily destroyed individual, Kasaoka City, Okayama Prefecture, coll. T. Sato, 16 Sep. 2020. RUMF-ZC-7652, 1 male (TL 37.0 mm, CL 6.5 mm) , 1 female (TL 38.6 mm, CL 6.8 mm) , Kasaoka City , Okayama Prefecture, coll. H. Nakajima, 17 May 2023. RUMF-ZC-7424, 1 male (TL 89.5 mm, CL 16.1 mm) , Ako City , Hyogo Prefecture, coll. T. Ueda, 22 Apr. 2022. RUMF-ZC-7431, 1 female (TL 60.3 mm, CL 10.3 mm) , same data as in RUMF-ZC-7424. RUMF-ZC-7432, 1 male (TL 62.6 mm, CL 12.5 mm) , same data as in RUMF-ZC-7424. RUMF-ZC-7433, 1 female (TL 92.3 mm, CL 15.7 mm) , Ako City , Hyogo Prefecture, coll. T. Ueda, 12 Jun. 2022. RUMF-ZC-7488, 2 females (TL 67.9 mm, CL 13.0 mm; TL 72.5 mm, CL 13.1 mm), Ako City, Hyogo Prefecture, coll. T. Ueda, 11 Mar. 2023 . RUMF-ZC-7499, 2 males (TL 46.3 mm, CL 8.3 mm; TL 70.0 mm, CL 12.5 mm), Ako City, Hyogo Prefecture, coll. H. Nakajima, 16 May 2023 .

Diagnosis. Carapace with or without tiny anterolateral spines ( Fig. 5A–E ). A1 somite dorsal processes distally acute or blunt ( Fig. 5D, E ). Distal margin of second segment of A2 peduncle extending anteriorly beyond eyes ( Fig. 5A, C ). Mandibular palp present ( Fig. 5F ). Raptorial claw dactylus with 4 ( Fig. 5H ) or 5 teeth ( Fig. 5G ); extensor margin without basal notch. TS5 lateral process blunt lobe in posterior view ( Fig. 5J ). AS 1–5 without SM carinae. Telson dorsal carinae strongly rounded; primary teeth short, apices obtuse ( Fig. 5M, N ). Postanal carina absent ( Fig. 5L ). Eye stalk without black band dorsally ( Figs. 5A–E , 6A–E ). A2 scale without black pigments ( Fig. 6A, C ).

Colour in life. Body entirely pale or dull green ( Fig. 6B–E ). Posterior margin of carapace, TS6–8 and AS 1–5 blackish. Lateral margins of AS 1–5 whitish ( Fig. 6C ). Posterior margin of proximal segment of uropodal exopod blackish ( Fig. 6A–E ).

Remarks. Clorida rotundicauda can be distinguished from the other congeners by the following particulars ( Ahyong et al. 2008): A1 somite dorsal process with low carina terminating in blunt angle ( Fig. 5D ); carapace usually without anterolateral spine ( Fig. 5C ); mandibular palp present ( Fig. 5F ); TS5 lateral process with blunt lobe ( Fig. 5I, J ); telson with obtuse, rounded teeth ( Fig. 5M, N ); and telson postanal carina absent ( Fig. 5L ). Most of the Japanese specimens examined in the present study have these morphological characters, but some minor variations are found.

First, the anterolateral corner of the carapace has a small but distinct spine only the right side in a large male (RUMF-ZC-7424, TL 89.5 mm; Fig. 5A ) or a small but distinct anterolateral spine on both sides of the carapace in the largest female (RUMF-ZC-7433, TL 92.3 mm; Fig. 5B ), a relatively large male (RUMF-ZC-7499, TL 70 mm) and a small female (RUMF-ZC-7652, TL 38.6 mm). Second, the largest female (RUMF-ZC-7433, TL 92.3 mm, Fig. 5E ) and the smallest female (RUMF-ZC-7652, TL 38.6 mm) are armed with a tiny acute spine on the dorsal process of the A1 somite, but the spine is usually absent and rounded in the other specimens examined ( Fig. 5D ), suggesting this is not related to their size or sex. Third, the movable SM teeth of the telson are present in small specimens (n=3, TL 37.0– 46.3 mm), but they are absent in large specimens (n=7, TL 60.3–92.3 mm); this might be related to the growth instead. Fourth, the lateral margin of the basal prolongation of the uropodal protopod is crenulate in some specimens (n=3, TL 67.9–92.3 mm), but it is smooth in the others (n=7, TL 37.0– 89.5 mm). It is possible that this variation is observed in large individuals.

According to Ahyong et al. (2008), C. choprai ( Tweedie, 1935) (type locality: Port Swettenham, Selangor, Malaysia), which Manning (1979, 1995) treated as a junior synonym of C. rotundicauda , might be a distinct species. Our Japanese specimens are more similar to the holotype of C. rotundicauda from Taiwan than the material reported by Manning (1979) from Phuket, Thailand, in the shape of the cornea. In the holotype ( Ahyong et al. 2008: fig. 67b; female, TL 70 mm) and our specimens, the anterior margin of the cornea is flattened ( Fig. 5A–E ), whereas in the specimens from Thailand ( Manning 1979: fig. 1a, b) and from Malaysia ( Tweedie 1935: fig. 1; the type material of Squilla choprai ), the anterior margin of the cornea is strongly bilobed. Our specimens examined are confidently identified as C. rotundicauda s.s. based on the corneal character.

This is the first record of C. rotundicauda from Japanese waters and represents the northernmost record of the species. The male specimen (RUMFZC-7424) is designated as the standard specimen for the new Japanese name (Maruo-meboso-shako) proposed here.

Distribution. Phuket, Thailand ( Manning 1979; Ahyong & Naiyanetr 2002); Port Swettenham, Selangor, Malaysia ( Tweedie 1935, as Squilla choprai ); Serangoon River, Singapore ( Tweedie 1935, as Squilla choprai ); Tsimei (= Fujian) ( Schmitt 1931, as Chloridella rotundicauda ) and Zhejiang ( Dong et al. 1983), China; Taiwan (the type locality) ( Miers 1880; Ahyong et al. 2008); and Japan (this study). Among these localities, the records from Thailand, Malaysia and Singapore could be based another species, C. choprai , currently regarded as a junior synonym of C. rotundicauda , as mentioned above (see Ahyong et al. 2008). Distribution in Japan ( Fig. 11 ): Okayama Prefecture and Hyogo Prefecture, both located in the northeastern part of the Seto Inland Sea.

Ecological note. Mud flat, often mangrove associated areas ( Ahyong et al. 2008). All the specimens examined were collected from intertidal mud flats nearby river mouths, where did not have mangrove areas ( Fig. 6F ). Ahyong et al. (2008) also stated that C. rotundicauda was associated with the upogebid mud shrimp, Austinogebia edulis (Ngoc-Ho & Chan, 2002). In our field survey, however, any association between C. rotundicauda and upogebids were not confirmed. In Okayama Prefecture, another squillid, Cloridopsis scorpio (Latreille in Latreille, Le Peletier, Serville & Guérin, 1828) has been also reported from the same habitat ( Nakajima & Ariyama 2022). Only C. japonica has been reported in the Seto Inland Sea so far, this is the second Clorida species there. Clorida japonica and C. rotundicauda have not been found in the same place.

Figures

FIGURE 5. Clorida rotundicauda (Miers, 1880). A, D, F, G, I–M, RUMF-ZC-7424, male, TL 89.5 mm; B, E, N, RUMF- ZC-7433, female, TL 92.3 mm; C, H, RUMF-ZC-7432, male, TL 62.6 mm. Photographed after preservation in ethanol. A–C, anterior cephalothorax, dorsal view; D, E, anterior cephalothorax, right lateral view, A1 somite dorsal process (arrows); F, left mandibular palp (arrow); G, H, right raptorial claw, lateral view; I, right TS5–7, dorsal view; J, right TS5, posterolateral view, lateral lobe (arrow); K, AS6, uropod and telson, right lateral view; L, uropod and telson, ventral view; M, N, AS6, uropod and telson, dorsal view. Scale bars: 5 mm. Photograph credit: H. Nakajima.

FIGURE 6. Clorida rotundicauda (Miers, 1880). A, RUMF-ZC-7424, male, TL 89.5 mm, photographed after about 1 month preservation in ethanol; B, C, RUMF-ZC-7433, female, TL 92.3 mm, photographed after freezing; D, RUMF-ZC-7652, male, TL 37.0 mm, photographed after anesthesia by clove oil; E, RUMF-ZC-7652, female, TL 38.6 mm, photographed after anesthesia by clove oil; F, collection habitat in Hyogo Prefecture, western Japan. Scale bars: left bar, 10 mm (A–C); right bar, 5 mm (D, E). Photograph credit: H. Nakajima.

FIGURE 11. Map showing the occurrences of five Clorida species and Cloridina ichneumon in Japan. Record of C. japonica at Nagasaki Prefecture, Kyushu Island (based on Komai 1927) is approximately plotted because of limited locality data.