Description ofGerres chrysops sp. nov. From Thailand and redescription ofGerres setifer (Hamilton, 1822) andG. Decacanthus (Bleeker, 1865) (perciformes: Gerreidae)

Abstract

Gerres chrysops, a new gerreid species from the Gulf of Thailand, is described on the basis of 29 specimens, 58–83 mm in standard length (SL). A small-sized species (less than 100 mm SL), it is characterized by a silvery-gold sheen on the head and trunk, vivid yellow or yellowish-hyaline fins in life, two supraneural bones (formula 0/0/2/) and dorsal fin rays usually IX, 10. The new species is similar toG. decacanthus (Bleeker, 1865) andG. setifer (Hamilton, 1822), which are redescribed. being similarly small valid gerreid species characterized by two supraneural bones. Together, the three species comprise “theGerres setifer complex.”Gerres chrysops differs from bothG. decacanthus andG. setifer in life and fresh colors, the body being silvery-gold with vivid yellow or yellowish dorsal, caudal, anal and pelvic fins, and yellowish-hyaline pectoral fins (vs. silver body with hyaline fins in the latter two species).Gerres setifer differs fromG. chrysops andG. decacanthus in having the last dorsal fin spine longer than the penultimate spine (vs. almost same length or shorter), usually ten dorsal fin spines and nine soft dorsal rays (vs. usually IX, 10), and 8 or 9 lower series gill rakers (vs. usually 7).Gerres decacanthus differs fromG. chrysops andG. setifer in having a shorter head, lesser body depth at the first anal fin spine base, lesser body width at the pectoral fin base, and shorter second dorsal and third anal fin spines. The new species is currently known only from Angsilla, near Bangsaen, and around Si Chang Island, northeastern Gulf of Thailand.Gerres decacanthus inhabits southern Chinese waters andG. setifer is currently known from the Bay of Bengal to the Andaman Sea.