Sicydiinae T.N.Gill 1860
Creators: name: Donaldson, James
name: Maeda, Ken
name: Iida, Midori
name: Kobayashi, Hirozumi
name: Ebner, Brendan C.
name: Tran, Hau Duc
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Perciformes
Gobiidae

description: RESULTS
Surveys recorded four sicydiine species which represent first records for Vietnam: Sicyopterus lagocephalus, Sicyopus zosterophorus, Stiphodon atropurpureus, Stiphodon percnopterygionus; and additionally Stiphodon multis-multisquamus (Table I). Across all five streams, maximum stream width did not exceed 7 m and maximum depth did not exceed 1.5 m (Table I). Surveys at all sites were conducted within 250 m from the mouth of the stream.
We recorded S. lagocephalus in all streams surveyed, however they did not appear to be abundant, with no more than 10 individuals observed at each site. It was identified by its characteristic body colouration (Fig. 1D) in the field and identification was verified in the laboratory using the mouth morphologies (smooth upper lip with a median cleft and a lateral cleft on each side; a prominent tubercle immediately behind the median cleft; ridge beneath the upper lip has a row of protuberances), number of soft rays in the second dorsal and pectoral fins (11 and 19 respectively), and size of scales on the occipital region and nape (similar size to the lateral scales) of the preserved specimens (Fig. 2A). Although S. lagocephalus has a broad distribution from the Comoros in the Western Indian Ocean to French Polynesia in the South Pacific Ocean (Keith et al., 2015), this new record represents a range extension of approximately 900 km southwest from Hong Kong (Mr. Tony Nip, Pers. Obs.; Fig. 3).
Sicyopus zosterophorus was recorded in three of five streams and was generally in low abundance. All of the S. zosterophorus observations occupied the upper catchment above significant waterfalls/barriers. Males were identified by an orange posterior half of the body with black bands on the orange area (Figs 1C, 2B) and the females by a translucent body with large scales having blackened margins covering the anterior to posterior parts of the body (Fig. 2C). This species has previously been recorded from southern Japan, Taiwan, mainland China, Philippines, Palau, Indonesia, Papua New Guinea, Solomon Islands, Vanuatu, New Caledonia, and Fiji (Keith et al., 2015). The current record of S. zosterophorus from Vietnam (as with the following two species) represents a range extension of approximately 700- 1,100 km southwest from mainland China (Fig. 3).
Stiphodon atropurpureus was found in all five streams surveyed and was moderately abundant in three of the streams. It was identified by the characteristic colouration and markings on the body and fins (males with metallicblue body and black dorsal fins with red margins; females with many black spots along the second dorsal-fin rays, a submarginal black line in the anal fin) (Figs 1F, 2D, E) and scales on the anterior half of the nape in males and on the anterior half of the occipital region in females. It has been recorded in southern Japan, Taiwan, mainland China, Philippines, Malaysia, and Indonesia (Keith et al., 2015; Maeda and Palla, 2015) (Fig. 4).
In the current study, only a single individual of S. percnopterygionus was observed, collected and preserved. This specimen was a male and identified by black, falcate first dorsal fin, black markings below the eyes, and a black blotch on upper part of the caudal fin among other characters (Fig. 1E). The ten soft rays in the second dorsal fin and 14 rays in the pectoral fin were also confirmed in the laboratory from the specimen (Fig. 2F). The previously known habitats are southern Japan, Taiwan, mainland China, Philippines, Guam, and Palau (Keith et al., 2015; Maeda and Palla, 2015) (Fig. 4).
In the current survey, S. multisquamus was the most abundant sicydiine recorded, however this was primarily driven by the high numbers encountered in Stream 1. In contrast, S. multisquamus was absent or in low abundance in other streams surveyed. Both males and females were identified by nine to 11 dark grey transverse bars laterally on the body, two or three light-coloured, transverse bars on the occipital region and nape, and fine black spots on the pectoral fin rays. As mentioned earlier this sicydiine had previously been reported from Vietnam (Maeda et al., 2015) (Fig. 4).
For completeness we also recorded other fish and fauna in the streams, however, these other taxa were not the focus of observations. This included some diadromous species of genera: Anguilla, Awaous, Rhinogobius, Kuhlia, and Eleotris, non-diadromous freshwater fish, Schistura carbonaria Freyhof & Serov, 2001, Poropuntius sp., Poecilia reticulata Peters, 1859 (an alien species), an estuarine/marine fish that facultatively inhabit freshwater environments as juveniles (Lutjanus), and amphidromous snails (Septaria sp. and Cli-Clithon sp.) across the surveyed sites.
description: Published as part of Donaldson, James, Maeda, Ken, Iida, Midori, Kobayashi, Hirozumi, Ebner, Brendan C. & Tran, Hau Duc, 2023, New distributional records of four amphidromous gobies (Gobioidei: Sicydiinae) in continental Vietnam, pp. 467-472 in Cybium 47 (4) on pages 469-470, DOI: 10.26028/cybium/2023-019, http://zenodo.org/record/12713800