A review of present knowledge of larvae of the Calopterygoidea (Zygoptera) of the Oriental realm, including keys to families and known genera Author Orr, Albert G. W. text Zootaxa 2024 2024-08-23 5497 2 209 243 http://dx.doi.org/10.11646/zootaxa.5497.2.3 journal article 305046 10.11646/zootaxa.5497.2.3 97257e17-d512-4a6e-a85b-b6af22d488fd 1175-5326 13618317 B3C66D95-3585-4920-BE93-A44D33FB2FBB Family Philogangidae The single genus Philoganga is known from four large species ranging from the eastern Himalaya, northern Myanmar , Thailand and Indochina to southern China . The larvae of three species are known, and are generally similar, Fraser (1938) described and figured P. montana (Hagen) , Chao (1948 , 1953 ) discussed Chinese species, including P. robusta Navás , and the most detailed descriptions are available for P. vetusta Ris ( Asahina 1967 , Xu 2016 , Ng 2024e ). The larvae ( Fig. 24 ) are found among stones in clear wooded streams in hill country up to 1200m . Fraser (1938) reported P. montana as inhabiting “...torrential mountain streams, clinging to the underside of stones or rocks or hiding up in clefts of rocks.”. Mature larvae are easily distinguished by their massive head, eight segmented antennae ( Fig. 25 ), (although Asahina (1967) reported some specimens of P. vetusta with only seven antennal segments), long tapered saccoid terminal gills and large size. As far as is known all species bear a cluster of long strong subocular spines on the anterior gena; the prementum ( Fig. 26 ) is broad, with rounded lateral margins bearing short spines in their anterior half, a slightly produced anterior median lobe with short median cleft. I was able to make direct comparisons with an exuvia of P. montana collected in Nepal by S.G. Butler (see Kemp & Butler 2001 ), which had 8-segmented antennae, and, aside from its huge size (total length excluding antennae and caudal gills 40mm ) it differed only slightly from the allopatric P. vetusta .