Listrura costai

biology_ecology

Habitat and ecological notes. Rio Jurumirim is the main canal of a small coastal basin of approximately 65 km 2 which flows through well-preserved areas ofAtlantic forest in the mountain range of the Serra da Bocaina. The rio Jurumirim forms a grassy lowland that becomes partially, and sometimes fully, flooded during periods of high rainfall. In this region, the grass vegetation has replaced the original Atlantic forest probably due to human action. Most specimens of Listrura costai were collected in a narrow (about 1 m wide) and shallow (about 50 cm deep) clear water stream located in a swampy plain area densely vegetated with grass (Fig. 8). This site located in rio Jurumirim lowland, just upstream from a paved road (RJ- 155), is right next to the pipe that runs underneath the road, draining the stream into a larger tributary of the main river. Most specimens were collected in a shallower portion of this stream (about 10 cm deep) either in the mud bottom or the thin layer of litter covering it (Fig. 8 a). Some specimens were also collected at shallowest pools (less than 5 cm deep) adjacent to the stream (Fig. 8 b). The locality where the holotype was found has similar characteris

A new glanapterygine catfish of the genus Listrura (Siluriformes: Trichomycteridae) from southeastern Brazil, corroborated by morphological and molecular data

conservation

Conservation remarks. The extremely restrict distribution, together with a high specificity of its natural habitat (swampy streams in lowland plain areas that rarely occur in southern Rio de Janeiro State watersheds) and relative proximity of human settlements make L. costai prone of becoming critically endangered or even extinct in a very short time period due to effects of human activities or stochastic events. However, no studies about population or geographical range reductions are available. Considering the IUCN categories and criteria to evaluate threatened species (IUCN, 2001, 2010), the actual information about L. costai allows only apply the criterion D 2 (area of occupation less than 20 km ²) for the category Vulnerable (VU). Conservation status of L. costai may be better circumscribed with a detailed analysis of its population density. Approval of conservation measures for this area is important not only to preserve this species but also for the conservation of other endemic species, such as Rivulus lazzarotoi.

A new glanapterygine catfish of the genus Listrura (Siluriformes: Trichomycteridae) from southeastern Brazil, corroborated by morphological and molecular data

description

Description. Morphometric data given in Table 1. Body elongate, subcylindrical at anterior portion of trunk, and strongly compressed at caudal peduncle. Dorsal and ventral profiles straight. Skin papillae minute. Head depressed and trapezoidal. Snout blunt and slightly elongated. Mouth subterminal and narrow. Teeth conical, tips pointed and curved. Two rows of teeth in jaw. Premaxilla teeth 15 - 26; dentary teeth 13 - 21. Eyes anteriorly located on head, nearer to snout tip than to opercular patch of odontodes. Nasal, maxillary and rictal barbels well developed. 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 just posterior margin of opercular patch of odontodes. Tip of rictal barbel reaching between middle of interopercular patch of odontodes and posterior margin of opercular patch of odontodes. Anterior nostril opening anteriorly at base of nasal barbel. Posterior nostril located on anterior half of distance between anterior nostril and eye. Interopercular odontodes 8 - 12, opercular odontodes 6 - 8; odontodes conical, tips pointed and slightly curved.

A new glanapterygine catfish of the genus Listrura (Siluriformes: Trichomycteridae) from southeastern Brazil, corroborated by morphological and molecular data

diagnosis

Diagnosis. Listrura costai is autapomorphically distinct from its congeners by possessing a small anterior process on the first hypobranchial (vs. process absent; Fig. 3). The new species is also distinguished from its congeners, except L. nematopteryx and L. picinguabae, by possessing only one pectoral-fin ray (vs. two to four rays). It differs from L. nematopteryx and L. picinguabae by having an inferior row of dots extending only on posterior half of body (vs. over almost the entire body), and posterior tip of ceratobranchial 5 strongly concave (vs. slightly concave or straight; Fig. 3). It further differs from L. nematopteryx by possessing a discontinuous lateral midline row of spots (vs. continuous row), lateral processes of urohyal reaching the anterior region of posterior ceratohyal (Fig. 4) [vs. reaching the posterior region of posterior ceratohial; see fig. 4 B in Villa-Verde & Costa, 2006], more dorsal and anal-fin rays (8 - 9 vs. 7 - 8 and 8 - 9 vs. 6 - 8, respectively), and more opecular and interopercular odontodes (6 - 8 vs. 4 - 6 and 8 - 12 vs. 5 - 7, respectively). It further differs from L. picinguabae by possessing a longer head (head length 11.7 - 15.3 % SL vs. 1

A new glanapterygine catfish of the genus Listrura (Siluriformes: Trichomycteridae) from southeastern Brazil, corroborated by morphological and molecular data