Merodoras nheco

description

Description. — Specimens examined ranged from 23.0 to 54.4 mm SL. See Table 1 for counts and measurements and Fig. 1 for dorsal, lateral, and ventral views of holotype (MZUSP 90591, 40.8 mm SL). Body weakly elongate, wide and somewhat depressed anteriorly, deepest at dorsal-fin origin, gently tapering to slender caudal peduncle. Ventral surface weakly flattened. Anterior nares surrounded by short tubular skin located close to nostril tip; posterior nares larger than anterior, with a skin flap, not tubular, located at antero-superior portion of the orbit. Cephalic shield ornamented with distinct grooves and ridges. Interorbital fontanel divided by epiphyseal bar into a small rounded anterior portion, surrounded by mesethmoid and frontals, and large rounded posterior portion surrounded just by frontals. Nuchal foramina absent. Nuchal shield formed by anterior, middle and posterior nuchal plates (Fig. 2). Nuchal plates with straight to slightly concave lateral margins. Anterior nuchal plate wide, pentagonal, sutured to epioccipital Fig. 2). Epioccipital with no posterior process. Nuchal portion of cephalic shield flat to weakly angled in transversal cut. Six branchiostegal rays (n = 3

Merodoras nheco, new genus and species from Rio Paraguay basin, Brazil (Siluriformes, Doradidae), and nomination of the new subfamily Astrodoradinae

description

Gênero novo. Britski et al., 1999: 116 [citation and diagnosis].

Merodoras nheco, new genus and species from Rio Paraguay basin, Brazil (Siluriformes, Doradidae), and nomination of the new subfamily Astrodoradinae

distribution

Distribution. — Known only from flooded area of Paraguay basin called “ Pantanal Matogrossense, ” in western Brazil (Fig. 3). Ecological Note. — Merodoras nheco lives in lentic waters, most precisely in lakes in flooded areas of Pantanal. In most specimens, we found many parasites (Pentastomida) in their gas bladder, between the inner walls and its internal pleura. Pentastomida parasites are known to have a reptile as definitive host. According to Francisco Machado (pers. com.), the “ jacarés-do-pantanal ” (“ southern-caiman, ” Caiman crocodilus yacare) feed on Merodoras nheco when the lakes dry in the winter, and the fishes became easy to capture.

Merodoras nheco, new genus and species from Rio Paraguay basin, Brazil (Siluriformes, Doradidae), and nomination of the new subfamily Astrodoradinae

etymology

Etymology. — Specific name toponymic with reference to the town of Nhecolândia, the place where this species was discovered. The Portuguese nh is pronounced like the French or Italian gn or the Spanish ñ. The word nheco apparently does not have any particular significance other than having probably been a nickname for the town founder.

Merodoras nheco, new genus and species from Rio Paraguay basin, Brazil (Siluriformes, Doradidae), and nomination of the new subfamily Astrodoradinae