Parapenaeopsis cornuta ( Kishinouye, 1900 )

Parapenaeopsis cornuta ( Kishinouye, 1900) View in CoL

Figs 1 a View Figure 1 , 2 a View Figure 2 , 3 a View Figure 3 , 4 a View Figure 4 , 5 a View Figure 5 , 6 a View Figure 6 , 7 a, b View Figure 7

Penaeus cornutus Kishinouye 1900: 23, unnumbered text fig., p 1. 7 - figs 9, 9 A (type locality: Ariake, Japan). View in CoL

Parapenaeopsis cornutus – Kubo 1949: 374 (? in part – Taiwanese material), figs 7 Z, 10 B, 22 I, 32 C, D, 47 N, 63 A, B, 75 F, L, 78 L, 135 C, 136 A, B.

Parapenaeopsis cornuta View in CoL – Hayashi 1986: 67, fig. 26; 1992: 105, fig. 57 a-c; Liu and Wang 1987: 524, fig. 2; Liu and Zhong 1988: 208, fig. 129, pl. 6: 5; Hsu and Chan 2023: 224, figs 2, 6 b.

Kishinouyepenaeopsis cornuta View in CoL – Sakai and Shinomiya 2011: 499, figs 3 A, B, 4 F; De Grave and Fransen 2011: 216.

Material examined.

Japan • [ CBM ZC 3280 ]: Tosa Bay, Katsura-hama Beach , commercial trawler, 10–20 m, 28 Nov. 1996, 3 ♂♂, cl 15.6–17.4 mm, 1 ♀, cl 19.0 mm • [ NTOU M 02640 ]: Aichi, Minami-Chita, Toyohama fishing port , commercial trawler, 18 m, 31 Oct. 2024, 1 ♂, cl 20.7 mm • [ NTOU M 02641 ]: Aichi, Nishio, Isshiki fishing port , commercial trawler, 22.5 m, 14 Dec. 2024, 1 ♂, cl 14.3 mm, 3 ♀♀, cl 21.5–24.6 mm .

Taiwan • [ NTOU M 02355 ]: Yilan County, Dasi fishing port , commercial trawler, 10 Mar. 1985, 2 ♂♂, cl 14.5–18.4 mm • [ NTOU M 02356 ]: Yilan County, Dasi fishing port , commercial trawler, 5 Aug. 1982, 1 ♂, cl 22.9 mm, 1 ♀, cl 28.9 mm • [ NTOU M 02357 ]: Keelung City, commercial trawler, 12 Oct. 1990, 1 ♂, cl 14.5 mm • [ NTOU M 02358 ]: Changhua County, Wenzi fishing port , commercial trawler, 5 Aug. 2021, 3 ♂♂, cl 16.6–17.4 mm, 39 ♀♀, cl 17.2–22.0 mm • [ NTOU M 02359 ]: Chiayi County, Budai fishing port , commercial trawler, 26 May 1974, 2 ♀♀, cl 18.0– 18.7 mm • [ NTOU M 02360 ]: Chiayi County, Budai fishing port , commercial trawler, 20 Jan. 1995, 1 ♀, cl 18.2 mm • [ NTOU M 02485 ]: Chiayi County, Budai fishing port , commercial trawler, 2 Jul. 2002, 1 ♀, cl 13.6 mm • [ NTOU M 02361 ]: Kaohsiung City, Singda fishing port , commercial trawler, 24 Jul. 1984, 2 ♀♀, cl 16.1–17.0 mm • [ NTOU M 02362 ]: Kaohsiung City, Kaohsiung port, station 4 , 1 Mar. 1994, 2 ♂♂, both cl 18.1 mm • [ NTOU M 02363 ]: Kaohsiung City, Cijin , 25 Mar. 1996, 4 ♂♂, cl 18.6–19.5 mm, 7 ♀♀, cl 19.1–23.1 mm • [ NTOU M 02364 ]: Pingtung County, Donggang fishing port , commercial trawler, 28 Jul. 1985, 2 ♂♂, cl 15.1–16.8 mm, 2 ♀♀, cl 19.2–19.3 mm • [ NTOU M 02419 ]: No specific data, 2 ♀♀, cl 21.1–21.2 mm • [ NTOU M 02486 ]: No specific data, 2 ♂♂, cl 19.0– 19.2 mm, 2 ♀♀, cl 23.1–23.4 mm • [ NTOU M 02487 ]: No specific data, 1 ♂, cl 18.3 mm, 3 ♀♀, cl 16.2–22.8 mm .

Southern China • [ MBM 155050 View Materials ]: Fujian, Xiamen fish market , 05 F- 16, 3 Sep. 2005, 2 ♂♂, cl 18.1–18.7 mm, 2 ♀♀, cl 19.4–22.3 mm • [ MBM 155083 View Materials ]: Guangdong, Yangjiang, Zhapo, Dajiao hill , 54 - K 187 B, 18 Nov. 1954, 2 ♂♂, cl. 14.3–17.7 mm, 2 ♀♀, cl 15.7–16.8 mm • [ MBM 155080 View Materials ]: Hainan, Boao , stn 3, 8 Nov. 1990, 2 ♀♀, cl 12.0– 16.3 mm • [ MBM 155074 View Materials ]: Hainan, Sanya bay , stn 3, CJ 97 C- 164, 3–4 m, Nov. 1997, 1 ♀, cl 18.1 mm .

Diagnosis.

Rostrum more or less horizontal, straight, extending to distal segment of antennular peduncle and often reaching tip of antennular peduncle, armed with 6–8 (avg. 7.0, n = 27) dorsal teeth (excluding epigastric tooth), tip devoid of tooth and slightly curved upwards. Postrostral carina generally having a weak median pit and with posterior 1 / 4 broadened and obscure, extending posteriorly to 0.72–0.92 (avg. 0.85, n = 30) of carapace length. Longitudinal suture short and extending to about level of epigastric tooth. Pereiopods I and II with basial spines and epipods. Pereiopod III generally lacking basial spine, rarely a minute to small basial spine present only in males. Abdominal somites I and II lacking dorsal carina. Telson without lateral movable spinules. Males with endopod of pleopod II strongly modified into boot-like shape, distal margin straight or more often distinctly concave medially, anterodistal part bearing tuft of dense long stiff setae extending beyond distal margin; petasma lacking distomedian projection but with distolateral projections strongly elongated and horn-like, tip of horn distinctly protruded at outer side. Female thelycum with anterior plate mostly semi-quadrate to sometimes semi-circular and 0.74–0.95 (avg. 0.85, n = 16) as long as wide, anterior margin with median part occasionally slightly protruded, surface slightly sunken and rarely with median longitudinal furrow; posterior plate with weak median ovate boss, lateral parts as large semicircular process; tuft of setae behind posterior plate long and thick.

Coloration.

(Fig. 7 a, b View Figure 7 ) Body generally greenish to bluish gray and densely covered with dark green dots. Antennal flagellae and abdomen slightly banded. Tip of rostrum dark brown to reddish brown. Eyes black gray. Uropods of tail fan dark green to dark red and with yellowish margins. Thoracic appendages pinkish white. Pleopods with rami reddish. Tuft of long setae behind thelycum bluish. Color photographs verified belonging to this species are provided by Hayashi (1986: fig. 26) and Hsu and Chan (2023: fig. 6 b).

Distribution.

Known with certainty from Japan to Taiwan and southern China, intertidal to 32 m deep ( Liu and Zhong 1988). Perhaps more widely distributed west to India and south to northern Australia (see Remarks).

Remarks.

For those distinguishing characters found in this study to be useful in separating the species of the “ P. cornuta ” group (Figs 1 View Figure 1 – 6 View Figure 6 , Table 2 View Table 2 ), topotypic material of P. cornuta from Japan has the pereiopod III generally lacking a basial spine; postrostral carina with the posterior part faded and extending to a position with a distinct distance from the posterior margin of the carapace; male pleopod II with endopod boot-like and having the distal margin straight or medially concave; petasma with tip of horn distinctly protruded only at the outer side; thelycum with anterior plate generally semi-quadrate and slightly shorter than width; posterior plate bearing a weak median ovate boss and a tuft of long setae behind it. Specimens with the above characteristics from Japan [ CBM ZC 3280 , NTOU M 02641 View Materials ], Taiwan [ NTOU M 02358 View Materials ], and southern China [ MBM 155074] have 99.3–100 % similarity in the barcoding mtCOI gene (615 bp, Table 1 View Table 1 ) and can be safely considered as belonging to the same species. Of the 100 specimens (including 27 males) examined, only two males from Japan [ CBM ZC 3280 ] and Taiwan [ NTOU M 02356 View Materials ] have their pereiopods III bearing small basial spines (on both sides). As the median boss at the posterior plate of the thelycum is weak in this species, this boss is sometimes rather rudimentary in small females.

Although P. cornuta can be readily separated from the other species of the “ P. cornuta ” species group by a combination of characters (Table 2 View Table 2 ), it does not have a unique and conspicuous distinguishing character. Its number of rostral teeth, shape of the postrostral carina, pereiopod III lacking an basial spine and even body coloration are nearly identical with P. amicus and P. incisa (exact coloration still unknown). The petasma and boot-like endopod of the pleopod II in males, as well as the shape of the anterior plate of the thelycum and the tuft of hairs (including color of hairs) behind the thelycum, are almost the same between P. cornuta and P. maxillipedo (Figs 3 a, b View Figure 3 , 4 a, b View Figure 4 , 5 a, b View Figure 5 ). Only the median boss at the posterior plate of the thelycum is relatively lower (Fig. 5 a View Figure 5 ) than that of P. maxillipedo (Fig. 5 b View Figure 5 ), while the median part of the posterior plate is flattened or sunken in P. incisa (Fig. 5 d View Figure 5 ) and P. amicus (Fig. 5 c View Figure 5 ), respectively. Nevertheless, the characteristic shape of the thelycum is generally underdeveloped in small females of penaeids. Therefore, the posterior plate of the thelycum is very similar amongst small females of P. cornuta , P. maxillipedo , and P. incisa .

The lack of a unique, conspicuous character to distinguish P. cornuta from the other species of the “ P. cornuta ” group renders the verification of the distribution records of this species very difficult. The original description of P. cornuta ( Kishinouye 1900) also has not mentioned nor illustrated clearly the present distinguishing characters used for separating the species of the “ P. cornuta ” group. The whereabouts of the type of P. cornuta is not known, and it is not in the National Museum of Nature and Science, Tokyo (personal communication from Tohru Naruse) or the University of Tokyo (where Kishinouye studied, personal communication from Tomoyuki Komai). Nevertheless, there is no report nor evidence that there is more than one species of the “ P. cornuta ” group present in Japan (see Hayashi 1986, 1992; Kubo 1949). Thus, the Japanese specimens examined in this work can be treated as typical P. cornuta .

It has been considered that P. cornuta is widely distributed in the Indo-West Pacific from Japan to India and tropical Australia (see Chan 1998; Holthuis 1980, 1984; Pérez Farfante and Kensley 1997). Other than its records from Taiwan and southern China confirmed by the present material examined, reports of this species from other areas need verification. For example, there is the possibility that the photographs assigned to “ P. cornuta ” from Thailand ( Chaitiamvong and Supongpan 1992: pl. 44) and Australia ( Grey et al. 1983: fig. 39) may actually represent P. amicus or P. incisa as some molecular analyses ( Hurzaid et al. 2020; Fakhruddin et al. 2024) have already suggested that P. incisa is likely at least ranging to the Strait of Malacca or even to Bangladesh (see “ Discussion ” below).