Metapenaeus affinis (H. Milne Edwards 1837)
- Dataset
- On the penaeid shrimps of the genus Metapenaeus Wood-Mason in Wood-Mason & Alcock, 1891 (Crustacea, Decapoda, Penaeidae) of Taiwan
- Rank
- SPECIES
Classification
- kingdom
- Animalia
- phylum
- Arthropoda
- class
- Malacostraca
- order
- Decapoda
- family
- Penaeidae
- genus
- Metapenaeus
- species
- Metapenaeus affinis
description
(Figs. 1, 8 a)
diagnosis
Diagnosis. Rostrum with 6 – 9 (excluding epigastric tooth) teeth along entire dorsal border, generally straight and with tip curved upwards, more or less extending to tip of antennular peduncle. Pereiopod I with ischial spine absent to distinct. In males, basial spine of pereiopod III not particular elongated, merus of pereiopod V bearing basal notch accompanied with carinated and twisted tubercle. Telson with minute movable lateral spinules. Male petasma with distomedian projections very low and crescent shaped, reaching behind tips of distolateral projections. Female thelycum with anterior plate having posterior part much wider than anterior part; coxal projections of pereiopod IV round plate like and often concealing anterior plate but not extending to lateral plates, lateral plates as two overlapped rounded flaps without any sharp ridge and median longitudinal fissure. Coloration. Body generally greyish green and densely covered with dark dots. Antennal flagella, distal parts of pereiopods and pleopods reddish. Uropods red margined with distal parts somewhat greenish yellow.
discussion
Remarks. Metpenaeus affinis mainly occurs in southern Taiwan and rather common there. Amongst the species of this genus in Taiwan, M. affinis is most similar to M. ensis (De Haan, 1844). These two species can be distinguished by the following characters. The petasma has the distomedian projections very low in M. affinis (Fig. 1 b) but as huge protuberances in M. ensis (Fig. 3 b). The lateral plate of the thelycum has the posterolateral margins strongly folded anteriorly in M. ensis (Fig. 3 c) but not folded up at all in M. affinis (Fig. 1 b). In mature females the coxal projection of pereiopod IV is normal and not expanded in M. ensis, but round plate like and often concealing the anterior plate of thelycum in M. affinis. In mature males, the basal protuberance at the merus of pereiopod V is rounded in M. affinis (Fig. 1 d) but spiniform in M. ensis (Fig. 3 d). Moreover, the ischial spine of the pereiopod I in males is often (but not always) indistinct or absent in M. affinis but distinct in M. ensis. The tip of the rostrum is somewhat curved upwards in M. affinis (Fig. 1 a) but generally straight in M. ensis (Fig. 3 a). The posterior parts of the uropods are often greenish yellow in M. affinis (Fig. 8 a) instead of bluish purple in M. ensis (Fig. 8 c). Moreover, in large specimens the pereiopods are somewhat banded with red and while in M. ensis (Fig. 8 c) but non-banded in M. affinis (Fig. 8 a). Nevertheless, juveniles of these two species with gentalia not fully developed are rather difficult to separate.
distribution
Distribution. Widely distributed in the Indo-West Pacific from the Persian Gulf to Japan and Papua New Guinea, intertidal to 92 m deep (Miquel 1982; Pérez Farfante & Kensley 1997; Chan 1998).
materials_examined
Material examined. Taipei City, Taipei market, 7 May 1985, 1 male cl 18.5 mm (NTOU M 02305). Yunlin County, Mailiao, Station 1, 1 female cl 14.4 mm (NTOU M 02428). Chiayi County, Budai fishing port, 2 Jul 2002, 9 males cl 18.9 - 21.7 mm, 15 females cl 21.0 - 28.4 mm (NTOU M 02306); 25 Feb 2021, 1 female cl 21.6 mm (NTOU M 02412). — Dongshi fishing port, 12 Dec 2021, 2 males cl 22.2, 23.8 mm (NTOU M 02403). Kaohsiung City, Kaohsiung fishing port, Mar 1975, 4 males cl 16.0 - 22.3 mm, 4 females cl 15.8 - 22.8 mm (NTOUM 02312). — Neiwei market, 17 Oct 2019, 1 female cl 29.2 mm (NTOU M 02313). — Singda fishing port, 24 Jul 1984, 1 male cl 17.9 mm (NTOU M 02314). — Kaohsiung Port, 5 Jan 1995, 9 males cl 12.8 - 19.2 mm, 9 females cl 16.3 - 33.2 mm (NTOU M 02311); Station 1, 1 Mar 1994, 6 males cl 10.9 - 20.8 mm, 9 females cl 14.6 - 21.5 mm (NTOU M 02308); Station 2, 1 Mar 1994, 1 male cl 19.5 mm, 2 juveniles cl 8.6, 13.0 mm (NTOU M 02309); Station 3, 1 Mar 1994, 1 male cl 16.11 mm (NTOU M 02413); Station 6, 1 Mar 1994, 1 male cl 19.2 mm, 3 females cl 20.2 - 31.6 mm (NTOU M 02310). Pingtung County, Donggang fishing port, 27 Dec 1974, 2 males cl 19.4, 22.8 mm, 1 female cl 23.3 mm (NTOU M 02315); 21 Oct 1995, 1 male cl 22.15 mm, 1 female cl 18.6 mm (NTOU M 02414); 14 Aug 2015, 1 male cl 23.5 mm (NTOU M 02316); 9 May 2019, 1 male cl 22.2 mm, 4 females cl 23.9 - 28.3 mm (NTOU M 02317); 5 Mar 2021, 1 male cl 23.1 mm (NTOU M 02318). No Specific data, 1 female cl 34.4 mm (NTOU M 02429)