Listrura elongata, Costa & Feltrin & Mattos & Vilardo & Katz, 2025

Costa, Wilson J. E. M., Feltrin, Caio R. M., Mattos, José L. O., Vilardo, Paulo J. & Katz, Axel M., 2025, Relationships of a new fossorial Microcambevinae catfish species from southern Brazil supporting multiple dorsal-fin losses in Listrura (Siluriformes, Trichomycteridae), Zoosystematics and Evolution 101 (3), pp. 1177-1185 : 1177-1185

publication ID	https://doi.org/10.3897/zse.101.139205
publication LSID	lsid:zoobank.org:pub:5658205C-E4B7-46B7-BFEF-3FF050200594
DOI	https://doi.org/10.5281/zenodo.15807365
persistent identifier	https://treatment.plazi.org/id/D8FBB0CC-6006-5E98-B774-34D6FEBC2BF2
treatment provided by	Zoosystematics and Evolution by Pensoft
scientific name	Listrura elongata
status	sp. nov.

Treatment

Listrura elongata sp. nov.

Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 A – C View Figure 5 , Table 3 View Table 3

Holotype.

Brazil • 1 ex., 58.1 mm SL; Santa Catarina State: Camboriú Municipality: near the village of Cobra Fria and the road Estrada Morro do Gavião, in a stream tributary of the upper Rio Camboriú ; 27°06'22"S 48°45'21"W; about 50 m asl; 14 February 2023; C. R. M. Feltrin, leg.; UFRJ 14279 GoogleMaps .

Paratypes.

(all from Santa Catarina State: Camboriú Municipality: Rio Camburiú basin): BRAZIL • 3 ex., 20.5–44.7 mm SL; collected with holotype; UFRJ 14281 GoogleMaps ; 2 ex. (C & S), 40.3–43.8 mm SL; idem; UFRJ 14280 GoogleMaps ; 2 ex. (DNA), 20.2–22.2 mm SL; idem; UFRJ 13473 GoogleMaps ; 2 ex., 26.5–34.8 mm SL; idem; CICCAA 05057 GoogleMaps ; 1 ex., 49.0 mm SL; stream close to the street Rua Manuel Maturino Anastácio ; 27°05'32"S, 48°45'22"W; about 30 m asl; 6 February 2023; A. M. Katz and P. J. Vilardo, leg.; UFRJ 13418 GoogleMaps .

Diagnosis.

Listrura elongata is distinguished from all other congeners, except L. boticario , L. depinnai , and L. menezesi , by the absence of dorsal fin. Listrura elongata is immediately distinguished from L. boticarioi and L. depinnai , its two congeners of the subgenus Prolistrura lacking dorsal fin, by having a different colour pattern of flank, comprising the presence of minute dark brown dots on caudal peduncle and dorsal portion of flank that are smaller than the eye diameter (Fig. 2 View Figure 2 ), vs. dark brown dots larger than the eye diameter ( de Pinna and Wosiacki 2002: fig. 1; Villa-Verde et al. 2008, 2013). Listrura elongata is also distinguished from L. boticarioi , its hypothesised sister species (Fig. 1 View Figure 1 ), by having more dorsal (38 vs. 28–30) and ventral (32 or 33 vs. 28) caudal procurrent rays, more interopercular odontodes (11–13 vs. eight), and a larger eye (eye diameter 8.5–11.5 % of heel length vs. 6.0 % of heel length). Listrura elongata also differs from L. depinnai by having more vertebrae (52 vs. 45 or 46), more interopercular odontodes (11–13 vs. four), and a slenderer body (body depth 8.9–11.3 % SL vs. 12.3–12.7 % SL, caudal peduncle depth 8.4–12.6 % SL vs. 14.2–14.5 % SL). Listrura elongata differs from L. menezesi of the subgenus Listrura by having more teeth in the premaxilla (20 or 21 vs. 15–18) and dentary (20 vs. 12–16), more dorsal caudal procurrent rays (38 vs. 28–30), and more interopercular odontodes (11–13 vs. five to seven).

Description.

External morphology. Morphometric data appear in Table 3 View Table 3 . Body elongated, greatest body depth approximately at vertical through area midway distance between pectoral-fin base and anal-fin origin, trunk compressed, dorsal and ventral profiles almost straight (Figs 2 View Figure 2 , 4 View Figure 4 ). Anus and urogenital papilla in shallow cavity immediately anterior to anal-fin base. Head slightly depressed, subtrapezoidal in dorsal view, anterior profile convex (Fig. 3 View Figure 3 ). Minute skin papillae on anterior portion of ventral surface of head and lips. Eye small, round, positioned on anterior dorsal area of head, nearer snout tip than opercular patch of odontodes, separated by small interspace from posterior nostril (Fig. 3 View Figure 3 ). Posterior nostril approximately equidistant from orbit and anterior nostril (Fig. 3 View Figure 3 ). Mouth subterminal (Fig. 3 View Figure 3 ). Branchial membrane attached to isthmus only at its middle anterior point (Fig. 3 View Figure 3 ).

Barbels relatively long (Fig. 3 View Figure 3 ); nasal barbel reaching between opercular patch of odontodes and area just anterior to it, maxillary barbel reaching between pectoral-fin base and area immediately anterior to it, rictal barbel reaching between posterior limit of interopercular patch of odontodes and pectoral-fin base. Jaw teeth pointed, arranged in two rows. Total premaxillary teeth 20 or 21, outer row 8, inner row 12 or 13; total dentary teeth 20, outer row 8 or 9, inner row 11 or 12. Odontodes pointed (Fig. 5 B View Figure 5 ). Opercular odontodes 6 or 7, interopercular odontodes 11–13. Branchiostegal rays 6. Cephalic latero-sensory system represented by short postorbital canal with 2 pores above opercular patch of odontodes, connected to short lateral line on anterior portion of trunk, with 1 or 2 pores.

Dorsal fin absent. Anal fin small, rounded, total anal-fin rays 8 (ii + 6). Pectoral fin narrow, total pectoral-fin rays 2 or 3, all segmented and unbranched, first ray longer, second ray about one-third to half first ray length, third ray when present rudimentary. Pelvic fin and girdle absent. Caudal fin spatula-shaped, total principal caudal-fin rays 13 (II + 9 + II), total dorsal procurrent rays 38 (xxxvii + I – II), total ventral procurrent rays 32 or 33 (xxxi – xxxii + I).

Osteology. Mesethmoid thin, abruptly widening posteriorly, with narrow and straight cornu (Fig. 5 A View Figure 5 ). Lacrimal nearly rectangular, with pronounced postero-lateral pointed expansion (Fig. 5 A View Figure 5 ). Sesamoid supraorbital small, elliptical (Fig. 5 A View Figure 5 ). Premaxilla broad, sub-triangular in dorsal view, with narrow lateral expansion (Fig. 5 A View Figure 5 ). Maxilla straight, relatively short, slightly shorter than premaxilla, tapering laterally (Fig. 5 A View Figure 5 ). Autopalatine sub-rectangular in dorsal view, lateral margin slightly concave, medial margin weakly sinuous (Fig. 5 B View Figure 5 ). Autopalatine postero-lateral process short, dorsally directed (Fig. 5 B View Figure 5 ). Autopalatine articular facet for mesethmoid wide, without distinctive processes (Fig. 5 B View Figure 5 ). Metapterygoid small, subtrapezoidal (Fig. 5 B View Figure 5 ). Quadrate slender, L-shaped, dorsal process small, with short posterior expansion (Fig. 5 B View Figure 5 ). Hyomandibula long, anterior outgrowth narrow, anteriorly tapering and terminating in sharp tip (Fig. 5 B View Figure 5 ). Hyomandibular articular facet for opercle robust, without distinctive ventral expansion (Fig. 5 B View Figure 5 ). Opercle and interopercle slender; transverse length of opercular odontode patch about half length of dorsal hyomandibular articulation for neurocranium, transverse length of interopercular odontode patch about three-fourths that length (Fig. 5 B View Figure 5 ). Preopercle narrow and long (Fig. 5 B View Figure 5 ). Parurohyal with narrow and pointed lateral process and moderate posterior process, its length about two-thirds of length between anterior margin of parurohyal and posterior process base (Fig. 5 C View Figure 5 ). Parurohyal head with prominent anterolateral paired process (Fig. 5 C View Figure 5 ). Middle foramen of parurohyal small, elliptical (Fig. 5 C View Figure 5 ). Vertebrae 52. Ribs 2 or 3. Caudal skeleton comprising two hypural plates in contact, dorsal plate corresponding to hypurals 3–5, ventral plate corresponding to hypurals 1–2 and parhypural. Anal-fin origin at vertical through centrum of 33 rd vertebra.

Colouration in alcohol. Dorsum, flank and head pale yellowish grey with minute dark brown dots irregularly arranged (Figs 2 View Figure 2 , 3 View Figure 3 ). Dots smaller than eye diameter, on dorsum, dorsal portion of flank and caudal peduncle (Fig. 2 View Figure 2 ). Slightly larger dots concentrated on longitudinal midline line of flank anterior to caudal peduncle, longitudinal line on dorsal portion of flank, central and anterior portions of dorsal surface of head, and opercular, interopercular, and branchiostegal regions (Figs 2 View Figure 2 , 3 View Figure 3 ). Ventral surface of head and trunk yellowish white (Figs 2 View Figure 2 , 3 View Figure 3 ). Dark brown chromatophores concentrated on chin and branchiostegal region (Fig. 3 View Figure 3 ). Fins whitish hyaline, with minute brown chromatophores on anal-fin base and brown pigmentation on middle of caudal fin (Fig. 2 View Figure 2 ).

Colouration in life. Similar to colouration in preserved specimens, with ground colour slightly darker (Fig. 4 View Figure 4 ).

Etymology.

From the Latin elongata (elongate), referring to the slender and long body of the new species.

Distribution and habitat notes.

Listrura elongata is only known from the Rio Camboriú basin, an isolated small river basin in the Atlantic Forest of southern Brazil (Fig. 6 View Figure 6 ). It was first found (i. e., a single specimen, UFRJ 13418 ) in the main channel of the upper Rio Camboriú, inside a plant remnant similar to a fern stem with earthy / clayey material attached to it. Ten days later, the same watercourse was intensively sampled, from 600 m above to 300 m below that collecting point, but no specimen was found, concluding that possibly the plant material was brought by a flood from some upstream tributary. Subsequently, about 15 different watercourses were investigated in neighbouring areas. The species was then found in a small stream tributary of the upper Rio Camboriú, the type locality (Fig. 7 View Figure 7 ). It crosses a still forested segment at its right bank, but just below the type locality, the stream course reaches a deforested area occupied by cattle paddocks, which is followed by a large-scale rice plantation. The type locality is situated on a brief slope generating a weak water flow. The stream is about 100 cm wide and 1–35 cm deep, with clear water, except in eutrophicated areas, with great concentration of fungi and algae, where the water is turbid. There is a great concentration of amphibious herbs at the site where specimens were collected (Fig. 7 View Figure 7 ). The second collecting point, the type locality, is about 1.5 km away from the first one. Further field studies in neighbouring river basins were unsuccessful in finding other populations of L. elongata (see discussion below).