Bioacoustics of Cyclorma

Remarks. Davie (2002: 207) noted that varunid Cyclograpsus and allied genera differ morphologically from Sesarmidae sensu stricto in the “pattern of development of the grooves that direct respiratory water flow across the pterygostome, and in particular, a more or less clearly defined vertical groove running subparallel along the buccal cavity”, and “a strongly developed, typically stridulatory, sub-orbital crest that is relatively straight, and extends some distance across the lateral branchial region”. This suborbital crest of varunids is usually distinct even in female specimens. Since the original description by Nobili (1905) , and the additional observation by Nobili (1906) , no one has reconsidered the systematic position of Cyclograpsus lophopus nor reported on its morphological characters. Recent molecular studies examined several Cyclograpsus species but C. lophopus . Our observation of the type specimens (MNHN-IU-2008-10673, ex- MNHN-B12566; MNHN-IU-2008-20697, ex- MNHN-B32611) have confirmed that C. lophopus lacks a suborbital crest and a vertical groove on the pterygostomial region along the buccal cavern but has an oblique setose ridge ( Fig. 2 c). This indicates that C. lophopus should be placed in the family Sesarmidae . The other external morphological characters of C. lophopus are too distinct for the species to be accommodated in any of the existing sesarmid or gapsoid genera. This is especially true for the distinct entire contour of the carapace, including the eye peduncle ( Fig. 1 ), and the short and wide ambulatory legs with foliaceous disto-posterior angles of the meri ( Figs. 1 , 3 b–d). We thus establish a new genus, Cyclorma n. gen. , for this species. Cyclorma n. gen. is a monotypic genus at least for the present.