Sinotachidius, Huys & Ohtsuka & Conroy-Dalton & Kikuchi, 2005

Huys, Rony, Ohtsuka, Susumu, Conroy-Dalton, Sophie & Kikuchi, Yoshiaki, 2005, Description of two new species of Neotachidius Shen & Tai, 1963 (Copepoda, Harpacticoida, Tachidiidae) from Korean brackish waters and proposal of a new genus for Tachidius (Tachidius) vicinospinalis Shen & Tai, 1964, Zoological Journal of the Linnean Society 143, pp. 133-159 : 158-159

SINOTACHIDIUS GEN. NOV.

Diagnosis: Tachidiidae . Condition of rostrum, integumental windows and mouthparts unconfirmed. Genital and first abdominal somites fused in ♀ original segmentation marked by transverse surface ridge dorsally and laterally; midventral copulatory pore positioned near posterior margin of genital double-somite (after Song & Chang (1995: fig. 1b)). Anal operculum spinulose. Caudal ramus setae IV – V well developed and pinnate. Sexual dimorphism in antennule, P2 endopod, P3 exopod (?), P5, P6 and urosomal segmentation .

Antennule with numerous pinnate setae/spines; 7- segmented in both sexes; chirocer in ♂, with aesthetascs on segments 4, 6 and 7. Antenna with distinctly 2-segmented exopod; exp-1 with one seta, exp- 2 with 0–1 lateral and two apical setae; lateral endopodal spine proximally displaced. Maxilliped with 1(?) accessory seta on endopod; claw minutely pinnate.

P1–P4 enp-1 of normal size and with inner seta. Rami 3-segmented in P1–P4. P1 exp-3 with two outer spines, enp-3 with two inner setae. P3 enp-3 with five setae/spines. P4 enp-2 with one inner seta. Armature formula as follows:

Exopod Endopod P1 0.1.122 1.1.221 P2 1.1.222 1.2.221 P3 1.1.222 1.2.221 P4 1.1.122 1.1.221

P 2 ♂ enp-2 with outwardly directed spinous apophysis; enp-3 small, anterior surface without transverse spinular comb, outer spine and outer distal seta rudimentary, inner setae well developed.

P3 exopod ♂ presumably sexually dimorphic as in Neotachidius and Tachidius .

P 5 ♀ slightly bilobate, separating outer lobe from endopodal lobe; outer lobe with basal seta and four exopodal elements (one seta, three spines); endopodal lobe with four pinnate spines. P 5 ♂ medially fused (?); each with four spines and two setae.

P 6 ♀ represented by opercula closing off common genital slit, each with one seta. P 6 ♂ symmetrical; each member with two pinnate spines and naked outer basal seta.

Free-living. Freshwater or brackish habitats.

Type species: Tachidius (Tachidius) vicinospinalis Shen & Tai, 1964 = Sinotachidius vicinospinalis ( Shen & Tai, 1964) comb. nov.

Species inquirenda: Tachidius discipes Giesbrecht, 1881 sensu Song & Chang (1995) .

Etymology: The genus name is derived from the type genus Tachidius and the prefix sino, referring to the country of origin of the type species.

According to Shen (1979) S. vicinospinalis has been recorded from brackish and freshwater habitats in both Guangdong and Fujian Provinces. Ovigerous females were encountered in April