Orthomorpha Bollman, 1893

Genus Orthomorpha Bollman, 1893 View in CoL

Orthomorpha coarctata ( de Saussure, 1860) View in CoL

Polydesmus coarctatus de Saussure, 1860: 297 (D).

Paradesmus flavocarinatus Daday, 1889: 136 (D). Synonymized by Enghoff (2005). View in CoL

Orthomorpha coarctata View in CoL – Pocock 1895: 809 (R, M, K); Attems 1937: 62 (D); 1953: 179 (R); Jeekel 1968: 45 (M); Likhitrakarn et al. 2011: 12 View Cited Treatment (D, R, K), Golovatch and Wesener 2016: 47 (L).

Orthomorpha coarctata gigas Attems, 1927: 63 (D). Synonymized by Jeekel (1968). View in CoL

Asiomorpha coarctata View in CoL – Verhoeff 1939: 117 (D); Enghoff 2005: 95, 96 (R); Nguyen and Sierwald 2013: 1236 (L); Likhitrakarn et al. 2023: 71 (R); et auctorum.

Orthomorpha coarctata gigas View in CoL – Jeekel 1968: 45 (M); Golovatch 1998: 43 (K).

New material examined.

4 ♂, 13 ♀ ( SMF-011 ), Cambodia, Battambang Province, Sangker River , walls and vegetation along river, 25 m a. s. l., 13°06'6.45"N, 103°11'59.09"E, 18. 07. 2017, leg. P. Jäger GoogleMaps .

Records from Cambodia.

Koh Kong Province, Sre Ambel ( Attems 1953).

Remarks.

Orthomorpha coarctata ( de Saussure, 1860) is a pantropical anthropochore species which is often referred to the monotypic genus Asiomorpha Verhoeff, 1939 . However, in line with the comprehensive revision of the genus Orthomorpha by Likhitrakarn et al. (2011), we retain this species within Orthomorpha . This decision follows the reasoning of Jeekel (1968), who argued that the characters separating Asiomorpha from Orthomorpha (primarily the gonopod tip which is reduced to a single, simple lobe) are insufficient to warrant a distinct generic status when considering the full range of variation within Orthomorpha sensu lato.

Since some recent checklists, including one by the part of the present authors ( Likhitrakarn et al. 2023) and the global catalogue of Paradoxosomatidae ( Nguyen and Sierwald 2013) , have applied the generic name Asiomorpha , further studies have been using the name for consistency with these particular reference works. Further complicating this matter, the molecular analysis by Likhitrakarn et al. (2019) demonstrated that O. coarctata forms a distinct clade, genetically distant from other congeners. This pronounced genetic isolation renders the genus Orthomorpha polyphyletic, unless O. coarctata is treated within its own monotypic genus, Asiomorpha . However, the authors of that study themselves urged caution, noting that their phylogram was based on a single mitochondrial gene (COI) and should thus be regarded as provisional. To definitively resolve the phylogenetic relationships within the Orthomorphini and reveal the taxonomic status of Asiomorpha , future studies incorporating additional genetic markers are clearly warranted.

The present contribution, being a focused taxonomic review of the genus Orthomorpha in a specific region, requires a consistent generic concept. Therefore, our treatment here is based on the taxonomic framework established in the most recent revision of the genus ( Likhitrakarn et al. 2011), which includes the full taxonomic history of O. coarctata .