Acanthistius patachonicus (Jenyns, 1842)

Irigoyen, Alejo J., Gerhardinger, Leopoldo Cavaleri & Carvalho-Filho, Alfredo, 2008, On the status of the species of Acanthistius (Gill, 1862) (Percoidei) in the South-West Atlantic Ocean, Zootaxa 1813, pp. 51-59 : 54-57

Acanthistius patachonicus (Jenyns, 1842)

( Figures 1 , 2 B, 4 B, 5)

Plectropoma patachonica Jenyns, 1842: 11 –12; Perugia, 1890: 611.

Acanthistius patachonicus : Jordan & Eigenman, 1888: 348; Berg, 1899: 46–48; Devicenzi, 1924: 91 –92; Ringuelet & Arámburu, 1960: 62; Figueiredo & Menezes, 1980: 28 –29; Nakamura, 1986: 196 –197; Carvalho-Filho, 1999: 106. A. brasilianus: De Mahieu & Capezzani, 1974: 209 –227 (fig. 1); Ciechomski & Casia, 1976: 27 –36; San Roman, 1980: 1 –50; Dell´ Arciprete et. al., 1987: 67 –84; Cosseau, 2000: 94 –95; Rubinich, 2001: 1 –44; Irigoyen, 2006: 1 –47; Irigoyen & Venerus, 2008: 349 –343.

Type locality: Syntypes were collected by Darwin at two locations, both off the coast of Buenos Aires Province ( Argentina): one off the mouth of La Plata River, 40 fathoms (= 73 m) (TL: 15 inches ~ 38 cm), and two at 38° 20’ S (TL: 9 and 7.5 inches, ~ 23 and 19 cm) ( Fig. 1 ). Darwin sailed through the type location between August, 1832 and December, 1833 in a series of survey cruises onboard of the Beagle Voyage, commanded by Cap. Fitz Roy. Some of the materials stored in the collections of MACN (Buenos Aires) were collected in the general area of the first locality, and in the immediate vicinity of the second.

Type repository: BMNH London 1917.7.14.34–35, three syntypes; one dry specimen (uncatalogued).

Material examined: MZUSP 70739 São Paulo, Brasil (two specimens, TL: 12.6 cm, 17.2 cm); MZUSP 70740 São Paulo, Brasil (one specimen, TL: 17.5 cm); MZUSP 70741 Uruguay (one specimen, TL: 21.4 cm); MACN 5004 Argentina (two specimens, TL: 24.6 cm, 14.2 cm); MACN 4368 Argentina (one specimen, TL: 33.0 cm); MACN 4662 Quequen, Argentina (one specimen, TL: 24 cm); MACN 8211 Quequen, Argentina (five specimens, TL: 27 cm, 23.7 cm, 21.5 cm, 22.5 cm, 22.4 cm); MACN 5757 Golfo Nuevo, Argentina (three specimens, TL: 39 cm, 30 cm, 36 cm); MACN 4432 Quequen, Argentina (four specimens, TL: 23.2 cm, 23.5 cm, 30.5 cm, 30.2 cm); MACN 805 Mar del Plata, Argentina (two specimens, TL: 27.4 cm, 23.3 cm); MACN 6594 Golfo Nuevo, Argentina (one specimen, TL: 32 cm); MACN 4203 San Blas, Argentina (one specimen, TL: 25.4 cm); MACN 2293 (fourteen specimens, TL: 32 cm, 23.5 cm, 25 cm, 26 cm, 25.4 cm, 16.5 cm, 18.5 cm, 29.2 cm, 20.5 cm, 23.5 cm, 16.5 cm, 20 cm, 25.5 cm, 15.4 cm); MACN 5771 Argentina (one specimen, TL: 35.5 cm); MACN 1241 Golfo San José, Argentina (nine specimens, TL: 27.5 cm, 25.5 cm, 23 cm, 26.4 cm, 275 cm, 255 cm, 245 cm, 23 cm, 26 cm).

Diagnosis: Anal fin with 2–3 spines and 8–10 soft rays; caudal fin rounded; pectoral fins with 15–17 soft rays. Three or four large spines on the inferior margin of the preopercle, two of them ventrally directed. Lateral line with 67–70 pored scales. Pectoral fin not more than 28% longer than pelvic fin. Dark red, brownish or grey depending on depth and color of the habitat substrate; irregularly shaped dark spots on body and dorsal and anal fins usually forming dark bands on the sides and irregular vermiculated lines, well defined at all sizes. Up to 65 cm TL.

Field observations: Thousands of individuals were observed while conducting diving surveys in rocky reefs off northern Patagonia, from the NW of San Matías Gulf (41 º S) to Comodoro Rivadavia (46º S), many of them caught as part of sampling routines between 2000 and 2008 ( Irigoyen 2006; Irigoyen & Venerus 2008). Furthermore thousands of individuals were observed from fisheries captures in the north coast of Argentina (38º S).

Descriptive remarks: Jenyns (1842), Perugia (1890), Figueiredo & Menezes (1980), Nakamura (1986) and Carvalho-Filho (1999) reported that Acanthistius patachonicus is grey to brownish, with dark bands not always visible on the sides, and irregular lines “zigzagging” in different directions over the body, dorsal fins and anal fins. The lined “zigzag” pattern of A. patachonicus is visible in individuals of all ages ( Figueiredo & Menezes 1980; Carvalho-Filho 1999). Our observation of live and preserved specimens confirms that pattern ( Fig. 5 ). Reported ratio between the length of the pectoral and pelvic fins is in the range of 1.18 to 1.28 ( Figueiredo & Menezes 1980), and 1.12 to 1.27 in the specimens studied by us. De Mahieu & Capezzani (1976) counted 80–100 scales on the lateral line (n = 700), Nakamura (1986) reported 84–98, and Figueiredo & Menezes (1980) 68; clearly, the former authors were referring to the total number of scales on the lateral line (lateral scale series), and the latter to pored scales only (lateral line scales). In the specimens examined by us the number of pored lateral line scales ranged between 67 and 70. Coincidentally with Berg (1899) we observed three comparatively long and robust spines on the opercle and preopercle ( Fig. 4 B).

Figures

FIGURE 1. Geographic ranges of Acanthistius brasilianus (dotted line, 15 º to 23 º S) and A. patachonicus (solid line, 23 º to 48 º S). (1) Type locality of A. brasilianus (15 º S, off Ilehus); (2) Type localities of A. patachonicus, off Argentina (near mouth of La Plata River and 38 ° 20 ’ S).

FIGURE 2. Reference specimens. (A) Syntype of Acanthistius brasilianus (MNHN, Paris). (B) “ Topotypic ” specimen of A. patachonicus collected in the immediacy of one of the two type localities (MACN Buenos Aires 5004, 38.4 ºS, 1963, TL 24.6 cm, preserved in ETOH).

FIGURE 4. Opercular and preopercular spines. (A) Acanthistius brasilianus. (B) A. patachonicus.

FIGURE 5. Photographs of Acanthistius patachonicus, recently caught (top) and in its natural habitat Golfo Nuevo, Argentina 2006 – 2007 (bottom).