Aptychotrema Norman, 1926

Last, Peter R., Séret, Bernard & Naylor, Gavin J. P., 2016, A new species of guitarfish, Rhinobatos borneensis sp. nov. with a redefinition of the family-level classification in the order Rhinopristiformes (Chondrichthyes: Batoidea), Zootaxa 4117 (4), pp. 451-475 : 464

Genus Aptychotrema Norman, 1926

Type species. Rhinobatus (Syrrhina) bougainvillii Müller & Henle, 1841 (by subsequent designation, apparently of Séret and McEachran, 1986).

Description. Nostril relatively small, length subequal to internasal distance; posterior aperture relatively wide, not oblique to anterior aperture. Anterior nasal flaps bilobed, not fused to form a nasal curtain, and long-based with innermost edge (insertion) connected to snout lateral to and slightly inward of innermost corner of posterior aperture; anterior aperture small, suboval to subcircular, its medial edge partly formed by long outer lobe-like extension of anterior nasal flap; posterior lobe of anterior nasal flap low with almost straight, papillate, oblique margin; posterior margin of anterior aperture bordered by short and broad posterolateral nasal flap; posterolateral nasal flap extending well posteromedially as a free lobe, often almost to inner edge of nostril; posterior nasal flap relatively narrow, short based, often narrower than posterolateral nasal flap and base length about half nostril length. Lower jaw convex to very convex (more so in adult males); skin margin forming upper lip very strongly arched; 2–3 short lateral grooves at its angle; oral groove weak and confined to side of mouth and chin.

Species. A. rostrata (Shaw, 1794) , A. timorensis Last, 2004 , A. vincentiana (Haacke, 1885) .