Deiratonotus japonicus ( Sakai, 1934 )

Kawane, Masako, Wada, Keiji, Kitaura, Jun & Watanabe, Katsutoshi, 2005, Taxonomic re-examination of the two camptandriid crab species Deiratonotus japonicus (Sakai, 1934) and D. tondensis Sakai, 1983, and genetic differentiation among their local populations, Journal of Natural History 39 (45), pp. 3903-3918 : 3910-3914

Deiratonotus japonicus ( Sakai, 1934)

( Figures 2 , 3 , 6 )

Paracleistostoma japonicum Sakai 1934, p 321 –322, Figure 26; Sakai 1935, p 219 –221, Figure 117, Plate 60 Figure 3 ; Sakai 1939, p 634, Figure 104, Plate 68 Figure 3 .

Camptandrium japonicum: Sakai 1976, p 618 –619, Plate 212 Figure 1 .

Deiratonotus japonicu s: Miyake 1983, p 164, Plate 55–56; Wada 1995, p 417, Plate 118–10; Nakasone and Irei 2003, p 271, Figure 37.

Deiratonotus tondensis Sakai 1983, p 41 –42, Plate 8-D; Nakasone and Irei 2003, p 271, Figure 37.

Material examined

Syntypes: three males, Shimoda , Shizuoka Prefecture, January 1933, collected by T. Sakai (KPH-NH0107898) ; one male (10.36 mm CW), Tonda R., Wakayama Pref., November 1977, coll. T. Sakai (Senckenberg-Mus. 28971) ; one male (6.12 mm CW), one female (10.10 mm CW), Isuzu River , Shizuoka Pref., 8 August 2002, coll. K. Wada (OMNH-Ar 6879) ; one male (5.84 mm CW), Yukashi Lagoon , Wakayama Pref., 26 April 2002, coll. K. Wada and M. Kawane (OMNH-Ar 6880) ; one male (9.80 mm CW), Ohta R., Wakayama Pref., 27 April 2002, coll. K. Wada and M. Kawane (OMNH-Ar 6881) ; one male (9.43 mm CW), Tsuni R., Wakayama Pref., 27 April 2002, coll. K. Wada and M. Kawane (OMNH-Ar 6882) ; one male (9.14 mm CW), one female (9.55 mm CW), Hiki R., Wakayama Pref., 27 April 2002, coll. K. Wada and M. Kawane (OMNH-Ar 6883) ; one male (7.81 mm CW), one female (7.68 mm CW), Fukuro R., Wakayama Pref., 27 April 2002, coll. K. Wada and M. Kawane (OMNH-Ar 6884) ; two males (7.41–8.94 mm CW), one female (7.23 mm CW), Tonda R., Wakayama Pref., 14 March 2002, coll. K. Wada and M. Kawane (OMNH-Ar 6885) ; one male (5.91 mm CW), one female (8.30 mm CW), Urauchi Bay, Kohchi Pref. , 10 July 2002, coll. K. Wada (OMNH-Ar 6886) ; one female (9.30 mm CW), Fukiage R., Kohchi Pref. , 13 July 2002, coll. K. Wada (OMNH-Ar 6887) ; one female (6.28 mm CW), Shimanto R., Kohchi Pref. , 12 July 2002, coll. K. Wada (OMNH-Ar 6888) ; one male (7.52 mm CW), one female (8.96 mm CW), Takahama R., Kumamoto Pref., 8 August 2001, coll. S. Yodo (OMNH-Ar 6889) ; one male (7.13 mm CW), one female (9.39 mm CW), Amikake R., Kagoshima Pref., 2 October 2002, coll. T. Kishino (OMNH-Ar 6890) ; one male (6.98 mm CW), one female (7.36 mm CW), Miyashi R., Kagoshima Pref., 18 April 2001, coll. A. Nomoto (OMNH-Ar 6891) .

Diagnosis

Carapace flat and anteriorly broadened. Anterolateral borders cut into three obtuse teeth, the foremost of which corresponds to outer orbital angle. Chelipeds equal and slender in both sexes but some male individuals have one larger. Tips of fingers spoon-shaped and somewhat hairy. Anterior pleopod strongly bent basally and pointed, with sparse hairs.

Description

Carapace flat and anteriorly broadened. Granulation on carapace visible under the microscope but some individuals have no granulation. A number of dull elevations on gastric, cardiac, hepatic, and branchial region of carapace. Anterolateral borders cut into three obtuse teeth, the foremost of which corresponds to outer orbital angle. Posterolateral borders rapidly converge backwards. Posterior border straight and much wider than front. Front narrow, with anterior border about one-third of carapace width and divided into two lobules. Eyestalk thick, much shorter than front, and cornea does not reach outer orbital angle. Basal segment of antenna short and quadrate, placed in the orbital hiatus. Epistome short and pterygostomian regions furry. Ischium of outer maxilliped as long as its width, its antero-inner angle triangularly produced. Merus somewhat broader than its length and as long as ischium, its external angle rounded.

Chelipeds equal and slender in both sexes but some male individuals have one larger, with a large truncated tooth near base of movable finger. Tips of fingers spoon-shaped and somewhat hairy. Of ambulatory legs, the first and the fourth pairs shorter than the second and third pairs. The latter two longer than the former and about one and a half times as long as carapace. Each segment very sparsely hairy in both sexes but some males thickly hairy.

The first segment of the male abdomen very short, and the second to fourth segments fused together, and the fifth segment narrowed in the distal portion. Female abdomen broad and telson widely triangular. Anterior male pleopod strongly bent basally and pointed, with sparse hairs.

Distribution

Distributed in western Japan from Kanagawa Prefecture to Okinawa Prefecture: Hayama, Kanagawa Pref.; Izu Shimoda, Shizuoka Pref.; Isuzu R., Sizuoka Pref.; Owase, Mie Pref.; Yukashi Lagoon, Ohta R., Tsuni R., Hiki R., Fukuro R., Tonda R., Wakayama Pref.; Urauchi Bay, Fukiage R., Shimanto R., Kohchi Pref.; Kita R., Miyazaki Pref.; Takahama R., Kumamoto Pref.; Amikake R., Miyashi R., Kagoshima Pref.; Aha R., Fuku R.,

Takazato R., Okinawa Pref. ( Sakai 1934, 1976, 1983; Terada 1995; Yamanishi et al. 2001; Nakasone and Irei 2003; this study).

Remarks

Deiratonotus tondensis Sakai, 1983 has been assigned to junior synonymy with D. japonicus , as shown in the present study. This species differs in features of the carapace, chelipeds, and the first pleopod of the male from a congeneric species, Deiratonotus cristatus (De Man, 1895) , which is the type-species of the genus. The carapace of D. cristatus has a transverse ridge on cardiac and mesobranchial regions and the lateral margins are closely pubescent without teeth, while D. japonicus has no ridge on carapace, lateral margins are not pubescent and have three teeth. Chelipeds are hairy at the tip in D. japonicus , but not in D. cristatus . The male pleopod has four stout subdistal spines on the tip in D. cristatus , while there are no spines in D. japonicus .

Figures

Figure 1. Sampling localities of Deiratonotus specimens. 1, Isuzu R., Shizuoka; 2, Yukashi Lagoon, Wakayama; 3, Ohta R., Wakayama; 4, Tsuni R., Wakayama; 5, Hiki R., Wakayama; 6, Hukuro R., Wakayama; 7, Tonda R., Wakayama; 8, Urauchi Bay, Kohchi; 9, Fukiage R., Kohchi; 10, Shimanto R., Kohchi; 11, Takahama R., Kumamoto; 12, Amikake R., Kagoshima; 13, Miyashi R., Kagoshima.

Figure 2. A male specimen having morphological characteristics of Deiratonotus japonicus, collected in the Isuzu River, Shizuoka (OMNH-Ar 6879). Scale bar: 5 mm.

Figure 3. A male specimen having morphological characteristics of Deiratonotus tondensis, collected in the Tonda River, Wakayama (OMNH-Ar 6885). Scale bar: 5 mm.

Figure 6. Male and female specimens of Deiratonotus japonicus. (A–C) Male from the Isuzu River, Shizuoka (OMNH-Ar 6879); (D) male from the Tonda River, Wakayama (OMNH-Ar 6885); (E) female from the Isuzu River, Shizuoka (OMNH-Ar 6879). (A, D) Cheliped; (B, E) abdomen; (C) first pleopod. Scale bar: 1 mm.