Common Name
Menni Skate
Year Described
Gomes & Paragó, 2001
Identification
Disk spade-shaped with a slightly concave to convex anterior margin. Snout very long. Pectoral fins angular. Tail about 50% of TL, and has low skin folds on both sides. There are two dorsal fins, separated from each other by a distance less than one half of first dorsal base. The caudal fin consists of a moderately developed lobe.
Body is smooth above, with dermal denticles restricted to snout. Interorbital and interbranchial rough. There are several orbital thorns and 2-7 spiracular thorns. Nuchal thorns present (5-7). Scapular thorns present (2-4). Median thorns present on midline of body anterior to pelvic base (18-25). Tail with 25-43 median row of thorns and one lateral thorn row on each side with 6-26 thorns each. Up to three thorns (1-3) present between the dorsal fins. Ventral surface smooth like dorsum.
Several osteological and clasper differences between D. trachyderma and D. mennii described in Moreira et al., 2011.
Color
Uniformly brown above, without markings. Underside paler with brown edges.
Size
Adults from 950-1544mm TL or 734-1100mm disk width.
Habitat
Demersal from 133-513m.
Range
Known only from off southeastern Brazil.
References
Díaz de Astarloa, J.M., E. Mabragaña, R. Hanner and D.E. Figueroa. 2008. Morphological and molecular evidence for a new species of longnose skate (Rajiformes: Rajidae: Dipturus) from Argentinean waters based on DNA barcoding. Zootaxa 1921:35-46.
Moreira, R.A., U.L. Gomes, & M.R. de Carvalho. 2011. Morphological description of Dipturus mennii (Chondrichthyes: Elasmobranchii: Rajidae) and its differentiation from Dipturus trachyderma. Zoologia 28 (1): 97–111.
Soto, J.M.R. and M.M. Mincarone. 2001. Dipturus diehli sp. nov., a new species of skate (Chondrichthyes, Rajidae) from southern Brazil. Mare Magnum v. 1 (no. 1): 3-6.
Other Notes
Described in the same year, Dipturus diehli (Soto & Mincarone, 2001) shares most major morphological characters with D. mennii. Díaz de Astarloa et al., 2008 differentiates them by extent of body denticles and number of nuchal thorns (5-6 in mennii and 8 in diehli) but these characters are somewhat variable between sexes and individuals. Moreira et al., 2011 considers D. diehli to be a synonym of D. mennii. Fishbase and the Catalog of Fishes still consider D. diehli valid and separate. Information on the status of these two apparently sympatric skates is needed.
I will keep the two as describing the same species as per the most recent published reference in 2011.