Geothelphusa marginata marginata, Naruse, Shokita & Shy, 2004

Naruse, Tohru & Shokita, Shigemitsu, 2004, A New Species Of The Freshwater Crab, Previously Assigned To Geothelphusa Miyazakii (Miyake & Chiu, 1965) (Crustacea: Decapoda: Potamidae), From Yaeyama Group, Southern Ryukyus, Japan, Raffles Bulletin of Zoology 52 (2), pp. 555-562 : 558-560

Geothelphusa marginata marginata

Japanese name: Murasaki-Sawagani ( Figs. 2a, b , 3 )

Geothelphusa miyazakii - Minei, 1973: 214, Fig. 8, 9G, H (part); 1981: 80 (part), Pl. 2 (lower); Sakai, 1976: 562 (English text), 347 (Japanese text) (part); Hirata et al., 1988: 25 (part), plate (middle of p. 25); Environment Agency, 1991: 228 (part); Okinawa Prefecture, 1996: 382 (part); Shokita, 1996: 348; Segawa, 2000: 243 (part); Kasai & Naruse, 2003: 283 (Part).

Geothelphusa sp. 2 - Yoshigou, 1999: 22, Pl. IIL (Part).

Material examined. – All specimens of G. m. marginata were collected in Ishigaki Island, Yaeyama Group, Southern Ryukyus, Japan.

Holotype – male, CL 27.7 mm, RUMF-ZC-59, a stream of Mt. Omoto-Dake (type locality), coll. Tohru Naruse & Yoko Okamoto, 11 Jul.2001.

Paratypes – 2 females, CLs 27.7, 27.9 mm, RUMF-ZC-87, data same as holotype ; 2 males, CLs 22.4, 26.8 mm, 1 female, CL 28.0 mm, NSMT-Cr 15172, upstream of Sukubaru Dam Reserve , coll. Tohru Naruse, 9 Aug.2001 ; 1 male, CL 26.7 mm, 1 female, CL 26.0 mm, NSMT-Cr 15173, a stream of Mt. Omoto-Dake , coll. Tohru Naruse, 11 Aug.2001 ; 1 male, CL 29.9 mm, CBM-ZC 6723, a stream of Mt. Omoto-Dake , coll. Hsi-Te Shih & Tohru Naruse, 9 Apr.2002 ; 2 females, CLs 28.3 32.1 mm, CBM-ZC 6724, a stream of Mt. Omoto-Dake , coll. Ryoko Segawa, 19 Mar.1997 .

Others – 2 males, CLs 21.7, 22.2 mm, RUMF-ZC-60, a stream of Mt. Omoto-Dake , coll. Ryoko Segawa, 19 Mar.1997 ; 3 males, CLs 14.4–20.9 mm, 1 female, CL 21.1 mm, ZRC 2003.0596 , a stream of Mt. Omoto-Dake , coll. Tohru Naruse, 22 Mar.2001 ; 1 male, CL 26.2 mm, 2 females, CLs 25.6, 27.2 mm, ZLKU 12648 , a stream of Mt. Omoto-Dake , coll. Y. Hashiguchi, 31 Jul.1968 ; 3 males, CLs 19.2–27.1 mm, 3 females, CLs 20.1–23.4 mm, ZLKU m1092, a stream of Mt. Omoto-Dake , coll. Y. Hashiguchi, 31 Jul.1968 ; 1 male, CL 27.5 mm, HMNH-C9 , Ohama , coll. Hidenori Yoshigou, 11 Aug.1999 .

Diagnosis. – Carapace with convex anterolateral margin, frontal margin slightly concave medially, cervical groove distinct as Geothelphusa species, barely connected from distinct H-shaped gastric groove to epibranchial tooth.

G1 sinuous, subterminal segment with small knob on proximal outer margin, proximal inner margin roundly swollen.

Carapace, chelipeds, and ambulatory legs purple, fingers of chelipeds, articulations of ambulatory, and about distal half of dactylus yellow/orange.

Distribution. – Ishigaki Island, Yaeyama Group, Southern Ryukyus, Japan.

Remarks. – Geothelphusa marginata marginata , can be easily differentiated from G. m. fulva by their live colouration. However, morphological differences are limited to the size of the proximal outer knob of the subterminal segment of G1 (small in G. m. marginata vs. large in G. m. fulva ), the condition of the cervical groove (barely connected from Hshaped gastric groove to epibranchial tooth vs. visible between H-shaped gastric region to hepatic region), and the shape of the frontal margin (slightly concaved medially vs. almost straight). Because G. m. marginata and G. m. fulva do not have large differences even in G1, subspecific status are considered for these two taxa.

Geothelphusa marginata marginata has a similar colouration to G. miyazakii , but the former tend to have softer colour than G. miyazakii . Furthermore, G. miyazakii has bright a, G. m. marginata (holotype, RUMF-ZC-59), dorsal view; b, G. m. marginata (holotype, RUMF-ZC-59), ventral view; c, G. m. fulva (paratype, RUMF-ZC-75); d, G. miyazakii (RUMF-ZC-76).

yellow rings on articulation of ambulatory legs and their dactylus are totally yellow.

Yoshigou (1999) recorded Geothelphusa sp. 2 from Ishigaki and Iriomote Islands and G. sp. 3 from Iriomote Island. As far as I examined his materials, G. sp. 2 and G. sp. 3 correspond to G. m. marginata and G. m. fulva , respectively. Geothelphusa sp. 2 of Iriomote Island is most likely a misidentification due the choice of unsuitable characters, such as relative width of the cornea and the direction of the projection of anterolateral margin. Furthermore, Yoshigou (1999) reported ambulatory leg proportions that are beyond the values found in the present study (Table 3).

Figures

Fig. 2. Colouration of Geothelphusa marginata marginata, G. m. fulva, and G. miyazakii.

Fig. 3. Geothelphusa marginata marginata. a, carapace, dorsal view; b, carapace, frontal view; c, left mandible; d, maxilla; e, gonopod 1, ventral view; f, gonopod 1, dorsal view; g, gonopod 2. a, b, e-g, RUMF-ZC-59 (holotype); c, d, RUMF-ZC-87. Scales: a, b, 10 mm; c–g, 1 mm.