Listrura picinguabae

biology_ecology

Habitat notes The new species was collected in narrow (about 50 cm wide) and shallow (about 20 cm deep) streams in a dense tropical forest (Mata Atlantica). Individuals were found buried in the litter bottom. No other fishes were observed, but tadpoles (unidentified) were present.

A new glanapterygine catfish of the genus Listrura (Siluriformes: Trichomycteridae) from the southeastern Brazilian coastal plains.

description

Description Morphometric data given in Table 1. Body elongate, subcylindrical on anterior portion of trunk, to strongly compressed on caudal peduncle. Dorsal and ventral profiles straight or slightly curved on anterior portion of body. Skin papillae minute. Head depressed, trapezoidal with square anterior portion in dorsal view (Fig. 3 B). Snout blunt. Mouth subterminal and narrow. Teeth conical, tips pointed and curved. Jaw teeth distributed in two rows. Premaxillary teeth 17 - 26; dentary teeth 13 - 15. Eyes anteriorly located on head, nearer snout tip than opercular patch of odontodes. Tip of nasal barbel reaching between posterior margin of interopercular patch of odontodes and posterior margin of opercular patch of odontodes. Tip of maxillary barbel reaching beyond posterior margin of interopercular patch of odontodes. Tip of rictal barbel reaching between middle of interopercular patch of odontodes and posterior margin of opercular patch of odontodes. Branchiostegal rays 6. Interopercular odontodes 7 - 10, opercular odontodes 6 - 8; odontodes conical, tips pointed and slightly curved. Dorsal and anal fins triangular. Dorsal-fin origin at vertical between centra of 34 th and 3

A new glanapterygine catfish of the genus Listrura (Siluriformes: Trichomycteridae) from the southeastern Brazilian coastal plains.

diagnosis

Diagnosis Listrura picinguabae is similar to L. nematopteryx, and distinguished from all other trichomycterids in possessing a single long pectoral-fin ray. It differs from L. nematopteryx in having the anal-fin origin anterior to dorsal-fin origin (dorsal-fin origin on vertical between base of 3 rd and 4 th anal-fin rays) to anal-fin origin slightly posterior to dorsal-fin origin, anal-fin origin on vertical through base of 2 nd dorsal-fin ray (vs. anal-fin origin always posterior to dorsal-fin origin, on vertical between 3 rd and 5 th dorsal-fin rays), dorsal-fin origin at vertical between centra of 34 th and 37 th vertebrae (vs. between 31 st and 34 th), 8 - 10 anal-fin rays (vs. 7 - 8), 6 - 8 opercular odontodes (vs. 4 - 6), 7 - 10 interopercular odontodes (vs. 5 - 7), and lateral process of urohyal reaching posterior region of anterior ceratohyal (vs. reaching posterior region of posterior ceratohyal) (Fig. 4).

A new glanapterygine catfish of the genus Listrura (Siluriformes: Trichomycteridae) from the southeastern Brazilian coastal plains.

discussion

Discussion Two species of Listrura, L. camposi and L. boticario, are known only from their holotypes. The lack of osteological information for these species impedes a complete analysis of phylogenetic relationships within the genus. However, it is possible that Listrura nematopteryx and L. picinguabae comprise a monophyletic assemblage, given the fact that the pectoral fin of these species consists of a single ray and the ray is in the form of a long filament. This condition is not present in any other trichomycterids thus far described. The lateral process of the urohyal is longer in L. nematopteryx than in L. picinguabae (Fig. 3). The apomorphic vomer bottle-shaped identified by de Pinna (1988) as a possible synapomorphy for Listrura and corroborated by Landim and Costa (2002), also occurs in L. picinguabae (Fig. 5). However, the vomer of L. picinguabae bears a short pointed posterior process, which is forked is some specimens.

A new glanapterygine catfish of the genus Listrura (Siluriformes: Trichomycteridae) from the southeastern Brazilian coastal plains.