Pseudohemiodon lamina (Günther 1868)

Provenzano-Rizzi, Francisco, Argüello, Pablo & Barriga-Salazar, Ramiro, 2022, The genus Pseudohemiodon (Siluriformes, Loricariidae) in Ecuador, with the description of a new species, Zootaxa 5129 (1), pp. 77-91 : 85-87

Pseudohemiodon lamina (Günther 1868)

Figures 3 , 4 , 5 , Table 3

Loricaria lamina Günther 1868a: 478 . Günther 1868b: 239, figs. 6–7. Regan, 1904: 294–295. Type locality: Xeberos (Jeberos), upper Amazon River, Peru.

Pseudohemiodon lamina Isbrücker, 1973:186 , (Lectotype selected). Isbrücker, 1980:121. Isbrücker, 1981:88. Ortega & Vari, 1986:17. Burgess, 1989:444. Isbrücker, 2001:29, 32. Isbrücker, 2002:28. Ferraris in Reis, et al., 2003:340 (as laminus). Ferraris, 2007:288 (as laminus). Barriga S. 2012:112. Sarmiento, et al. 2014:192. Rojas-Molina, et al. 2019:9 (references copied).

Material examined: All from Ecuador, Orellana Province: MEPN 5786 , 2 , 52.9–97.2 mm SL, Tiputini River, Lagoon Huaorani area , 4 km upstream from Guiyero, Napo River system, approx. 00°37’28”S 76°30’14”W, 04 Dec. 2006, R. Barriga &, J. Silva. MEPN 7901 , 2 , 34.0– 47.6 mm SL, Aguarico River, near Puerto Loja, Napo River system, approx. 00°52’57”S 75°13’30”W, 24 Jul. 1998, R. Barriga & D. J. Stewart. MEPN 8413, 166.3 mm SL, Tiputini River, 700 m downstream from the Huaorani Lagoon entrance, 00°37’18”S 76°29’43”W, 16 May 2008, R. Barriga & J. Silva. MEPN 16771, 168.9 mm SL, Tiputini River , 3 km upstream of Guiyero community, 00°37’30”S 76°29’43”W, 10 Jul. 2007, R. Barriga & J. Silva. MEPN 17464, 194.9 mm SL, Tiputini River , 3 km upstream of Guiyero community, 00°37’30”S 76°29’43”W, 10 Jul. 2007, R. Barriga & J. Silva. MEPN 17571 , 2 , 193.6 – 195.1 mm SL. Tiputini River , 1 km upstream from confluence with Chimbira River , Napo River system, approx. 00°37’31”S 76°31’09”W, 11 Jun. 2007, R. Barriga &, J. Silva. MEPN 17901 , 5 , 73.2–140.5 mm SL, Aguarico River , near Puerto Loja, Napo River system, approx. 00°52’57”S 75°13’30”W, 24 Jul. 1998, R. Barriga & D. J. Stewart. Pastaza Province: MEPN 13377 , 156.0 mm SL, Maranaco River , tributary of Curaray River , Napo River system, approx. 01°37’02”S 76°01’15”W, 05 Jan. 2014, R. Barriga. Sucumbios Province: MEPN 15095, 101.9 mm, Lagoon Allpamanga Cocha , 45 minutes from confluence Pañacocha-Napo Rivers , approx. 00º24’15”S 76º07’44”W, 22 Aug. 1992, R. Barriga, D. Granet & D. Dueñas .

Since the original description of P. lamina made by Günther (1868), the species is easily recognized among all its congeners by one distinctive character, the presence of two to four small plates in front of the gill opening on the ventral surface of the head ( Fig. 5 ). Our observations show that the small plates in front of the gill opening are present and are easy detected even in small specimens, between 60.0–70.0 mm SL. Additionally, this species is distinguishable from the other species in Ecuador by the absence of dark transverse bands, behind the dorsal-fin or over the caudal peduncle, in specimens larger than 55 mm SL, below this size, specimens can show up to eight transverse bands in this region ( Figs. 3 , 4 ). Also, small specimens lack the distinctive color pattern typical of small specimens of P. apithanos , and the body and head shape and contour are different from that observed in P. almendarizi and P. apithanos , in dorsal view ( Fig. 3 ). The head lateral borders in large specimens are somewhat concave ( Figs. 3 , 4 , 5 ), while in P. almendarizi small specimens and P. apithanos the borders are straight. The figure of P. platycephalus ( Kner, 1853 (4): lam, VI, fig. 2a) and the figure of P. laticeps , lectotype, BMNH 1895.5.17.113, available in the ACSI image database ( Morris et al. 2006) show concave lateral head margins, but P. platycephalus and P. laticeps are reported for the Paraná, Paraguay, Uruguay, La Plata rivers systems. Finally, the abdomen of P. lamina is completely covered with plates, in a similar way to the species P. almendarizi , P. apithanos , P. laticeps and P. unillano ( Fig. 5 ). The morphometric data of analyzed specimens is offered in Table 3 . In specimens between 73.2–101.9 mm SL counts are: plates in mid-lateral series 32; coalescent plates (double keel) 15–16, mode 15; posterior plates (single keel) 16–17, mode 16; thoracic plates (between posterior end of pectoral-fin base and origin of pelvic-fin base) eight to ten, mode nine. Premaxillary teeth 3/4–5/8, mode 5/6; dentary teeth 4/6–7/7, mode 6/7. Dorsal-fin rays i,6; pectoral-fin rays i,6; pelvic-fin rays i,5; anal-fin rays i,5; and caudal-fin rays i,10,i. In specimens between 127.3–194.9 mm SL counts are: plates in mid–lateral series, 31–32, mode 32; coalescent plates (double keel) 14–16, mode 15; posterior plates (single keel) 16-18, mode 17; thoracic plates (between posterior end of pectoral-fin base and origin of pelvic-fin base) eight to ten, mode nine. Premaxillary teeth 5/5–7/9, mode 7/7; dentary teeth 5/8–9/10, mode 8/8. Dorsal-fin rays i,6; pectoral-fin rays i,6; pelvic-fin rays i,5; anal-fin rays i,5; and caudal-fin rays i,10,i.

Geographical distribution: The specimens analyzed were captured in the Napo River system, Amazon River basin ( Fig. 6 ) .

Figures

FIGURE 3. a) P. almendarizi, MEPN 17903, 87.9 mm SL, holotype. b) P. apithanos, MEPN 18374, 97.5 mm SL. c) P. lamina, MEPN 15095, 101.9 mm SL. d) P. laticeps, MCP 9308, 126.1 mm SL. Dorsal views, scale bar 1 cm. Photos a), b) and c) by P. Argüello; d) by B. Calegari.

FIGURE 4. a) P. apithanos, MEPN 10578, 198.2 mm SL. b) P. apithanos, MEPN 19581, 171.6 mm SL. c) P. lamina MEPN 16771, 168.9 mm SL. d) P. laticeps MCP 9308, 126.1 mm SL. Dorsal views, scale bar 1 cm. Photos a), b) and c) by P. Argüello; d) by B. Calegari.

FIGURE 5. a) P. apithanos, MEPN 19581, 171.6 mm SL. b) P. lamina, MEPN 16771, 168.9 mm SL. c) P. laticeps, MCP 9308, 126.1 mm SL. Ventral views, head, mouth and abdomen cover, detail. Scale bar 1 cm. Photos a) and b) by P. Argüello; c) by B. Calegari.

FIGURE 6. Map of Ecuador showing the geographic distribution of Pseudohemiodon species. P. almendarizi, red star, type locality, P. apithanos, yellow triangles, P. lamina, black circles. Some symbols may represent more than one lot.