Parapenaeopsis tenella ( Bate, 1888 )

Hsu, Yen-Cheng & Chan, Tin-Yam, 2023, On the penaeid shrimps of the genus Parapenaeopsis Alcock, 1901 (Crustacea, Decapoda) from Taiwan, Zootaxa 5361 (2), pp. 221-236 : 229-231

Parapenaeopsis tenella ( Bate, 1888)

( Figs. 4 , 6e )

Penaeus tenellus Bate, 1888: 270 (type locality: Japan).

Parapenaeopsis tenella — Hall 1962: 26, figs 100, 100a, b; Racek & Dall 1965: 108, pl. 8-fig. 10, pl. 13-fig. 8; Yu & Chan 1986: 126., 1 unnumbered fig; Perez Farfante & Kensley 1997:121; Lee et al. 1999: 446.

Parapenaeopsis tenellus — Liu 1955: 16, pl. 4–2, 5–6–9; Dall 1957: 221, fig. 29.

Batepenaeopsis tenella — Sakai & Shinomiya 2011: 498, figs. 2A, 4C; De Grave & Fransen 2011: 213; Shinomiya & Sakai 2016: 505: figs 4–5.

? Batepenaeopsis moresbyensis Shinomiya & Sakai, 2016: 498 , fig 3 (type locality: Papua New Guinea).

Material examined. Keelung City, 29 Jun 1982, 1 female cl 16.7 mm ( NTOU M02392 ) ; 27 Feb 1989, 1 male cl 8.9 mm, 1 female cl 8.9 mm ( NTOU M02495 ) . Miaoli County, 20 Mar 2001, 2 males cl 9.0– 9.5 mm, 4 females cl 12.7–14.2 mm ( NTOU M02393 ) .

Diagnosis. Rostrum with 7–8 dorsal teeth but lacking epigastric tooth; horizontal and nearly straight, ventral border slightly concave, reaching between middle of second segment and middle of distal segment of antennular peduncle. Longitudinal suture long and extending to nearly posterior carapace. Pereiopods I and II bearing basial spines but lacking epipods. Pereiopod III without basial spine. Abdominal somites I–II without dorsal carina. Telson without movable lateral spinules. Male with normal endopod at pleopod II; petasma with small distomedian projections, distolateral projections triangularly elongated and directed proximolaterally. Female thelycum with anterior plate semicircular, surfaces sunken, posterior part with median longitudinal groove; posterior plate with anterior margin concave and broadly notched medially.

Coloration. Body generally reddish brown with color at posterior margins of abdominal somites deeper.

Distribution. Widely distributed in the Indo-West Pacific from Pakistan to Northern Australia and Japan; at depths of 5.5–50 m ( Pérez Farfante & Kensley 1997; Chan 1998).

Remarks. Parapenaeopsis tenella is rather uncommon in Taiwan. Shinomiya & Sakai (2016) recently split P. tenella into two species mainly by the length of rostrum and pereiopods, naming the long rostrum and pereiopod form as P. moresbyensis ( Shinomiya & Sakai, 2016) . The shape of the thyleum is also argued to be different between P. tenella and P. moresbyensis by Shinomiya & Sakai (2016) but the difference is very subtle and difficult to comprehend. Moreover, the two species appeared to be geogrpahically separated with P. tenella restricted to the north from Japan to the South China Sea while P. morebyensis is a southern species distributed from the South China Sea to Australia and India. The charateristics of the Taiwanese material, however, are intermediate between P. tenella and P. moresbyensis . The larger female from Keelung (NTOU M02392, Fig. 6e ) has shorter rostrum and pereiopods and fits the characteristics of P. tenella as defined by Shinomiya & Sakai (2016). The other two specimens from Keelung (NTOU M02495) both have the rostrum broken while the pereiopods are longer and fit the characteristic of P. moresbyensis . The two males from Miaoli (NTOU M02393) have shorter rostrum but longer pereiopods. Of the four females from Miaoli (NTOU M02392), two have longer rostrum but shorter pereiopods, one has longer rostrum and longer pereiopod I but shorter pereiopod IV (pereiopod V missing in this specimen) while the other with the rostrum broken and shorter pereiopods. Actually Shinomiya & Sakai (2016) already noticed that some speicmens in China they identified as P. tenella have characterisitc intermediate between P. tenella and P. moresbyensis . More extensive studies including molecular genetic analysis will be necessary to determine if P. moresbyensis is a valid species.

Figures

FIGURE 4. Parapenaeopsis tenella (Bate, 1888), a, c, female cl 13.5 mm (NTOU M02393); b, male cl 9.5 mm (NTOU M02393). a, carapace and anterior appendages, lateral view. b, petasma, ventral view. c, thelycum, ventral view. Scales: a, 5 mm; b, 1 mm; c, 3 mm.

FIGURE 6. a, Parapenaeopsis amicus V.C. Nguyên, 1971, female cl 29.5 mm (NTOU M02417). b, P. cornuta (Kishinouye, 1900), male cl 14.5 mm (NTOU M02357). c, P. hardwickii (Miers, 1878), female cl 30.3 mm (NTOU M02610). d, P. hardwickii (Miers, 1878), male (from Chan & Yu 1986, specimen lost). e, P. tenella (Bate, 1888), female cl 16.7 mm (NTOU M02392). f, P. venusta De Man, 1907, females cl 17.3 mm (NTOU M02395).