Diapoma Cope, 1894

Menezes, Naércio A. & Weitzman, Stanley H., 2011, A Systematic Review Of Diapoma (Teleostei: Characiformes: Characidae: Stevardiinae: Diapomini) With Descriptions Of Two New Species From Southern Brazil, Papéis Avulsos de Zoologia 51 (5), pp. 59-82 : 60

Diapoma Cope, 1894

Diapoma Cope, 1894a:67 (type-species: Diapoma speculiferum Cope1894a : by monotypy, compared with Tetragonopterus ); 1894b:92 (more complete generic description, states “allied to Hemigrammus ” but no similar characters listed, also states “peculiarly formed operculum displays a tendency towards that of Corynopoma ” Gill). – Eigenmann, 1914:34 (definition of genus, inclusion in Diapominae and in Glandulocaudinae ). – Eigenmann & Myers, 1929:467, 471 (key to glandulocaudine genera and description of genus, placed in Glandulocaudinae ). – Gregory & Conrad, 1938:321, 335 (placed in Glandulocaudinae following Eigenmann, Glandulocaudinae placed in Characinae (in part = American Characidae ). – Fowler, 1951:412 (listed, placed in family Stevardiidae and subfamily Stevardiinae ). – Travassos, 1951:53 (listed, considers Diapoma nomenclaturaly valid). – Nelson, 1964:59, 70, 143 (considers caudal pouch indicative of glandulocaudine relationship, discusses elongate opercle as an intermediate “condition” between that of male and female Corynopoma ). – Fowler, 1975:332 (listed). – Géry, 1977:335, 359, 362 (considered an “allied form” of Pseudocorynopoma but in key placed in couplet with Corynopoma ). Weitzman & Fink, 1985:1, 17, 109, 113 [caudal morphology illustrated, considered Glandulocauda , in part, of Géry 1964 (but not that of Eigenmann, 1911) a synonym of Diapoma , questions relationships to other glandulocaudines]. – Weitzman et al., 1988:383 (listed, placed in subfamily Glandulocaudinae , tribe Diapomini ). – Weitzman & Menezes, 1998:184 (placed in Glandulocaudinae , tribe Diapomini , discuss preliminary relationships). – Weitzman, 2003:224 (placed in subfamily Glandulocaudinae , tribe Diapomini ) – Miran- de, 2009:8 (placed in Characidae , subfamily Stevardiinae ). – Javonillo et al., 2010 (may not be a natural group).

Diagnosis: Diapoma is currently assigned to the tribe Diapomini together with Planaltina and Acrobrycon , the three genera differing from the remaining members of the Stevardiinae by (1) the presence of a caudal organ nearly equivalent in size and development in both males and females and (2) the presence of multiple series of scales (at least three or more) ventral to the lateral line series and extending posteriorly to form the dorsal border of the pouch opening. Diapoma can be distinguished from Planaltina by having the dorsal border of the pouch opening formed by 4 to 8 scales, one of them larger than the others ( Fig. 13 ), a feature also present in Acrobrycon ( Weitzman & Menezes, 1998, figs. 14 and 15) instead of just the 1 or 2 large scales present along the same border in Planaltina ( Menezes et al., 2003, figs. 19, 28, and 33). From Acrobrycon , Diapoma can be easily distinguished by its interrupted lateral line ( Fig. 10 ), with the short anterior segment having 7 to 22 pored lateral line scales whereas in all the species of Acrobrycon the lateral line is complete or nearly so with 51 to 68 pored scales.

Figures

FIGURE 10: Diapoma terofali, MZUSP 28268, adult male above, SL 42.0 mm and adult female below, SL 38.0 mm.

FIGURE 13: Diapoma terofali, MZUSP 28268, C&S, sexually active male, SL 42.0 mm; caudal-fin squamation of ventral portion of caudal-fin lobe, lateral view, left side. Arrow indicates larger scale.