Morphological development and occurrence patterns of larval and juvenile halfbeaks, Zenarchopterus spp., associated with mangrove flotsam in a shallow coastal area, Trang, southern Thailand.

Hemiramphid larvae and juveniles collected from surface mangrove flotsam (e.g.. leaves, twigs and seeds) in a shallow coastal area off Trang Province, southern Thailand, from June 2011 to July 2012, were identified as Zenarchopterus sp. 1 [n = 175, 5.4-36.7 mm in body length (BL)] and Zenarchopleriis sp. 2 (n = 41, 6.0-25.2 mm BL), based on dorsal- and analfin ray and myomere numbers, body proportions, and the presence of paired long nasal papillae. The two species were easily separable by their pigmentation patterns, Zenarchopterus sp. 1 possessing 6-8 dark transverse lateral bands on the body and a heavily pigmented dorsal fin, whereas Zenarchopterus sp. 2 lacked such distinctive pigmentation, instead having numerous melanophores scattered along the myomeres. Zenarchopterus sp. 1 occurred throughout the year, Zenarchopterus sp. 2 being restricted to the rainy season (May through October). [ABSTRACT FROM AUTHOR]