Myersina yangii ( Chen, 1960 )

Koreeda, Reo, Seah, Ying Giat, Izarenah, Md Repin & Motomura, Hiroyuki, 2025, Recognition of the girdled shrimpgoby, Myersina yangii (Actinopterygii, Gobiiformes, Gobiidae), from Taiwan, with notes on male color pattern and discovery of the species in Malaysia, Acta Ichthyologica et Piscatoria 55, pp. 309-315 : 309-315

Myersina yangii ( Chen, 1960)

English common name: girdled shrimpgoby New standard Malay name: Belodok Udang Belang Figs 1 , 2 , 3 , 4 , Table 1

Cryptocentrus yangii Chen, 1960. — Chen 1960: 10, fig. 1 (includes line drawing of female; type locality: off Fang-liaw, Taiwan).

Myersina yangii ( Chen, 1960). — Chen and Fang 1999: 216, unnumbered fig. (line drawing only; Taiwan). — Winterbottom 2002: 70 (text; comment on Satapoomin’s specimen from Phuket, Thailand). — Satapoomin 2011: 67 (list). — Greenfield and Randall 2018: 96, fig. 5 (underwater photograph: Cebu Island, Philippines). — Kodeeswaran et al. 2020: 219, fig. 1 (single female specimen: Tamil Nadu, India). — Allen and Erdman 2024: 975, numbered 3 figs. ( New Britain, Papua New Guinea; Bintan, Indonesia; Bali, Indonesia).

Myersina species — Allen and Erdmann 2012: 881, unnumbered fig. (underwater photograph: Bali, Indonesia).

Myersina sp. — Senou 2019: 1121, unnumbered figs. (single male specimen: southern Taiwan).

Material examined.

KAUM –I.193504 , male, 47.8 mm SL, off mouth of Jarum Mas River , Perak, Malaysia, bottom trawl, 17 January 2024 ; KAUM –I.113207 , male, 55.9 mm SL, off Dong-gang , Pingtung County, Taiwan, trawl, 7 March 2018 .

Identification and notes on diagnostic features.

The examined specimens were identified as belonging to the genus Myersina sensu Winterbottom (2002) , based on the following combination of characters, which closely matched the diagnostic features of that genus: gill membrane fused in ventral midline and forming free fold covering isthmus (Figs 3 , 4 ); cycloid scales on body; no scales on mid-nape, head, and pectoral-fin base; scales on posterior part of body larger than on anterior part (Fig. 1 B ); dorsal-fin spines elongated (Figs 1 , 2 ); sensory papillae on cheek forming transverse pattern (Fig. 2 ); and no teeth on vomer. Moreover, morphological features (documented below) matched the diagnoses and descriptions of Myersina (or Cryptocentrus ) yangii (except for anal-fin rays) given by Chen (1960), Greenfield and Randall (2018), and Kodeeswaran et al. (2020): gill membrane fused in ventral midline and forming free fold covering isthmus (Figs 3 , 4 ); longitudinal dark band absent on body (Figs 1 , 2 ); first dorsal fin with elongated spines and lacking a dark blotch distally (Figs 1 , 2 ); and pale spot absent on body and first dorsal fin (Figs 1 , 2 ).

The Malaysian specimen differed from other examples of the species in number of anal-fin rays [ 10 in former vs. 11 in Chen (1960), Chen and Fang (1999), Greenfield and Randall (2018), Kodeeswaran et al. (2020), and the present Taiwanese specimen]. However, conspecificity of the former and latter was confirmed by the remaining diagnostic features and the similarity of fresh color pattern given in the original description with that of the present Taiwanese specimen: silver-brown head and body; a bluish-silver oblique line on head (posteroventral to eye); upper and mid lateral longitudinal lines on body (see above; Figs 1 A , 2 A ); second dorsal fin with two pale (bluish) longitudinal lines (Figs 1 A , 2 A ). The former features were regarded as diagnostic characteristics of the species, being documented in the original description as “ A silvery but not very distinct longitudinal line from the origin of spinous dorsal obliquely downward through post-lower margin of eye to the median of maxillary, another same color line from upper edge of gill opening backward along the median of dorsal half of body to upper part of caudal base, but posterior part of this mark always disappeared. ” and “ the distinct coloration as uniform color of body with two silvery but faint longitudinal lines ” ( Chen 1960). This pattern was also observed in later published figures of live or fresh individuals of Myersina yangii (see Allen and Erdmann 2012; Greenfield and Randall 2018; Kodeeswaran et al. 2020). Among members of Myersina sensu Winterbottom (2002) and Greenfield and Randall (2018), only Myersina yangii has such diagnostic bands on the lateral head and body ( Smith 1959: as Cryptocentrus pretoriusi ; Chen 1960: as Cryptocentrus yangii ; Allen and Erdmann 2012; Greenfield and Randall 2018; Suzuki et al. 2021: as Cryptocentrus filifer ). Therefore, the difference in anal-fin rays between the Malaysian specimen and those considered in previous studies (see above), including seven syntypes, four West Papuan specimens, a single Indian specimen, and the present Taiwanese specimen, is regarded as an intraspecific variation, despite the number of anal-fin rays having been considered an important diagnostic character within Myersina (see Winterbottom 2002; Greenfield and Randall 2018).

The presently reported Taiwanese specimen had an incomplete scale patch of a few scales on the pre-pelvic region (Fig. 4 ), whereas Chen (1960) found no such scales, and the Malaysian specimen also lacked them (Fig. 3 ). It is possible that the scaleless condition of the latter may have been due to damage incurred during collection (by trawl).

Distribution.

Myersina yangii has been reported from Fang-liaw (type locality) ( Chen 1960) and Tong-kang, Taiwan ( Chen 1960); Liloan, Cebu Island, the Philippines ( Greenfield and Randall 2018); Bintan, North Sulawesi, Bali, and West Papua, Indonesia ( Allen and Erdmann 2012, 2024; Greenfield and Randall 2018); New Britain, Papua New Guinea ( Allen and Erdmann 2024); off the Andaman Sea coast of Thailand ( Winterbottom 2002; Satapoomin 2011); and Tamil Nadu, India ( Kodeeswaran et al. 2020) (Fig. 5 ). Therefore, the present Malaysian specimen represents the first record of the species from Malaysia.

Remarks.

Myersina species sensu Allen and Erdmann (2012) is recognized here as Myersina yangii due to having a transverse black band on the body around the anus, a diagnostic characteristic of the species according to Chen (1960) and Winterbottom (2002). However, the two specimens reported here lacked such a band. Because Chen (1960) mentioned that the diagnostic band only occurred in females, the present Malaysian and Taiwanese specimens are regarded as males. The tapered urogenital papillae of the two specimens support the present sex determination. Note that the character was treated as diagnostic for females of the species by Chen (1960) and Winterbottom (2002), whereas Greenfield and Randall (2018) regarded it as specifically diagnostic. Recent studies of M. yangii have only considered females, the figured individuals having a black band around the anus ( Allen and Erdmann 2012; Greenfield and Randall 2018; Kodeeswaran et al. 2020). Prior to Greenfield and Randall (2018), only a single female specimen had been figured in the original description ( Chen 1960; Chen and Fang 1999). To date, M. yangii is considered extinct in Taiwan ( Yang et al. 2024: 13). Although many examples had been collected in Taiwanese waters in 1958–1960 ( Chen 1960), Chen and Fang (1999) noted that more recent collections from Taiwan had been unsuccessful and suggested the possibility of the species being extinct in southern Taiwan due to the decline of suitable habitat. Because Myersina sp. sensu Senou (2019) was in fact M. yangii , the species has not become extinct in Taiwan.

The figured individual of Kodeeswaran et al. (2020) had a reddish body when fresh compared with other reports ( Allen and Erdmann 2012; Greenfield and Randall 2018; Kodeeswaran et al. 2020; this study). Elsewhere, the present Malaysian and Taiwanese specimens had a black blotch on the fifth and fourth spines of the first dorsal fin, respectively, Chen (1960) having noted “ a dusky patch on the fourth spine. ” Although such differences are regarded here as geographic or intraspecific variations, further clarification of color pattern differences between Indian populations and others is necessary. Note that female specimens figured in Chen (1960), Allen and Erdmann (2012), Greenfield and Randall (2018), and Kodeeswaran et al. (2020) lacked a black blotch on the first dorsal fin. Subsequent investigation may confirm the occurrence of such a blotch as a consistent feature of males of M. yangii (neither male nor female syntypes of the species were available to this study).

Two unidentified Japanese species, Myersina spp. 1 (“ Mihono-hagoromo-haze ”) and 2 (no Japanese name) sensu Suzuki et al. (2021), had similar color patterns to M. yangii but could be readily distinguished from the latter by the extent of first dorsal-fin spine elongation (not elongated in Myersina sp. 1 ; third spine only elongated in Myersina sp. 2 ; first to fourth spines elongated in M. yangii ) and the absence of a black blotch on the first dorsal fin, at least in males. Allen and Erdmann (2012) documented that M. yangii (as a Myersina species) is also present in the Ryukyu Islands, whereas M. yangii has not been recorded in Japanese waters. The record of M. yangii from the Ryukyu Islands is regarded as a misidentification with the two Japanese species in this study.

Figures

Figure 1. Photographs of Myersina yangii (KAUM – I. 193504, male, 47.8 mm SL, collected off the mouth of the Jarum Mas River, Perak, Malaysia). Fresh (A) and preserved (B) coloration.

Figure 2. Photographs of Myersina yangii (KAUM – I. 113207, male, 53.3 mm SL, collected south of Donggang, Taiwan). Fresh coloration (A) and preserved specimen temporarily stained with cyanine blue (B).

Figure 3. Head of Myersina yangii (KAUM – I. 193504, male, 47.8 mm SL) from Malaysia, temporarily stained with cyanine blue. Yellow dots, AN, PN, and other capital letters indicate sensory papillae, anterior nostril, posterior nostril, and sensory canal pores, respectively.

Figure 4. Head of Myersina yangii (KAUM – I. 113207, male, 53.3 mm SL) from Taiwan, temporarily stained with cyanine blue. Yellow dots, PN, other capital letters, and a pink dotted line indicate sensory papillae, posterior nostril, sensory canal pores, and anterior margin of scaled area, respectively.

Figure 5. Distribution of Myersina yangii; previous records based on specimens (circles) and underwater photographs (squares), and present Malaysian specimen (star).