Friday, September 9, 2022

[Ichthyology • 2022] Redefinition of Heptapterus (Heptapteridae) and Description of Heptapterus carmelitanorum, A New Species from the upper Paraná River Basin in Brazil


Heptapterus carmelitanorum
Azevedo-Santos, Deprá, Aguilera, Faustino-Fuster & Katz, 

in Deprá, Aguilera, Faustino-Fuster, Katz & Azevedo-Santos, 2022. 

Abstract
A new diagnosis and a new classification of Heptapterus are provided and a new species, H. carmelitanorum, is described. Heptapterus is diagnosed by the following character combination: adipose fin confluent with the caudal fin; non-bifurcate caudal fin; anal-fin insertion posterior to vertical through adipose-fin insertion; 10–23 anal-fin rays; anal fin not confluent with caudal fin; and extremely elongate body, with a head length of 16.1–24.9%SL. Species included in Heptapterus are H. borodini, H. carmelitanorum, H. carnatus, H. exilis, H. hollandi, H. mandimbusu, H. mbya, H. mustelinus, H. ornaticeps, and H. qenqo. Some of the character states diagnosing H. carmelitanorum among its congeners are the anal-fin insertion less than one eye diameter posterior to a vertical through the adipose-fin insertion (vs. more than one eye diameter in all congeners); the isognathous mouth (vs. slightly to moderately retrognathous, except H. borodini); and the keel formed by ventral procurrent caudal-fin rays shallow, far from reaching anal-fin base (vs. keel formed by ventral procurrent caudal-fin rays deep, continuing almost to the anal-fin base, except in H. borodini and H. hollandi).

Key Words: Chasmocranus’ brachynema, Grande River basin, Heptapterus mustelinus, Imparfinis borodiniImparfinis hollandi, Minas Gerais, Pariolius, Sapucaí River basin, Siluriformes

Heptapterus carmelitanorum, new species, holotype, coloration in life.

Heptapterus carmelitanorum, new species, holotype, MNRJ 53174, 144.3 mm SL;
a. Dorsal view; b. Lateral view; c. Ventral view.

Heptapterus carmelitanorum sp. nov., Azevedo-Santos, Deprá, Aguilera, Faustino-Fuster & Katz
 
Heptapterus’ sp.: - Azevedo-Santos et al. (2019) (listed in a survey).
 
Diagnosis: Heptapterus carmelitanorum differs from all congeners by possessing the anal-fin insertion less than one eye diameter posterior to a vertical through the adipose-fin insertion (vs. more than one eye diameter posterior). From all congeners, except H. borodini, by an isognathous mouth (vs. slightly to moderately retrognathous). It differs from all other congeners except H. borodini and H. hollandi, by the keel formed by ventral procurrent caudal-fin rays shallow, far from reaching anal-fin base (vs. keel formed by ventral procurrent caudal-fin rays deep, continuing almost to the anal-fin base, even though its anterior portion is devoid of fin rays) (Fig. 5). It differs from both H. borodini and H. hollandi by having an almost elliptical caudal fin (vs. lanceolate in H. borodini, obliquely truncate to falcate in H. hollandi; Fig. 6), the length of its dorsal lobe 18.3–19.3% SL (vs. 24.4–43.3% SL in H. borodini). Additionally, H. carmelitanorum differs from all other congeners, except H. carnatus, H. mbya, H. qenqo, and some specimens of H. hollandi, by having inconspicuous dorsal bars (vs. conspicuous). From H. borodini, H. carnatus, H. exilis, H. hollandi, H. mustelinus, and H. ornaticeps, by having 14–15 anal-fin rays (vs. 10–12 in H. borodini and H. hollandi; 18–21 in H. carnatus; 16–19 in H. exilis; 18–23 in H. mustelinus; and 19 in H. ornaticeps). Differs from H. exilis by the complete lateral line (in adults), continuous to base of hypural plate (vs. incomplete, not reaching dorsal-fin insertion). Heptapterus carmelitanorum further differs from H. hollandi by having i,6 dorsal-fin rays (vs. i,7).

Partial view (i.e., stretch) of the stream where the type specimens of Heptapterus carmelitanorum were sampled.

Etymology: The specific name is a noun in apposition derived from Carmelitanos (in Portuguese), the local appellation of people born or living in Carmo do Rio Claro (Minas Gerais, Brazil), the city where the species was discovered. The name is in honor of Carmelitanos, especially Ana Maria Vilela Soares, José Cândido de Mello Carvalho, Moara Lemos, and Carlos Roberto Bueno Júnior, for their contributions to biological science.


 Gabriel de Carvalho Deprá, Gastón Aguilera, Dario R. Faustino-Fuster, Axel M. Katz and Valter M. Azevedo-Santos. 2022. Redefinition of Heptapterus (Heptapteridae) and Description of Heptapterus carmelitanorum, A New Species from the upper Paraná River Basin in Brazil. Zoosystematics and Evolution. 98(2): 327-343.  DOI: 10.3897/zse.98.89413