Ariopsis simonsi ( Starks, 1906 )

Marceniuk, Alexandre P., Acero, Arturo, Cooke, Richard & Betancur-R, Ricardo, 2017, Taxonomic revision of the New World genus Ariopsis Gill (Siluriformes: Ariidae), with description of two new species, Zootaxa 4290 (1), pp. 1-42 : 35-39

Ariopsis simonsi ( Starks, 1906)

Canchimala Sea Catfish (English) Canchimala blanca (Spanish)

Figures 20 and 21 , Tables 2–4 and 12.

Galeichthys simonsi Starks, 1906:764 , Figs. 1–2 . Type locality: Callao, Peru. Holotype: USNM 53466. Ariopsis seemanni (non Günther), Chirichigno & Cornejo, 2001: 18.

Material Examined. Type-specimens. USNM 53466 (1, 215 mm Sl), Peru, Callao . USNM 284549 (3, 88– 117 mm Sl) Peru, Tumbes, Lower Rio Tumbes, NE Ar Las Paralles. Non type-specimens . AUM 57436 (1, 92 mm Sl), Peru, Lima ; INV PEC 6718 (2, 183– 210 mm SL), Colombia, Valle del Cauca, Buenaventura, La Barra-Juanchaco- Ladrilleros (4° 1' 0" N, 77° 28' 0" W), trawl, 3.4 m, Biomálaga . INV PEC 9087 (3, 183– 245 mm SL), Valle del Cauca, Mercado de Buenaventura, A. Acero P., 1999. Discarded Material: (7, 185– 274 mm SL), Valle del Cauca, Mercado de Buenaventura, 1998–2006.

Diagnosis. Ariopsis simonsi differs from its congeners as follows: from A. assimilis , from Mexico (Quintana Roo) to Honduras (Caribbean), the presence of an osseous medial groove (vs. absent; Figs. 3 and 21 ); from A. canteri , from Colombian Caribbean, the presence of an osseous medial groove (vs. absent; Figs. 3 and 21 ); from A. felis , from Massachusetts ( US) to Yucatán, Mexico (Caribbean), by its fleshy medial groove of neurocranium conspicuous or inconspicuous, but never surpassing posterior margin of eyes (vs. conspicuous and very long, always surpassing the posterior margin of eyes, Figs. 4 and 21 ), pterotic lateral margin convex, sometimes angled (vs. smoothly convex, Figs. 3 and 21 ), lateral margin of sphenotic straight, as wide medially as anteriorly (vs. notched, narrower medially than anteriorly, Figs. 3 and 21 ); from A. gilberti , from Mexico (EP), by 28–37 gill rakers on the first and second gill arches (vs. 40–42), fleshy medial groove of neurocranium conspicuous or inconspicuous, but never surpassing posterior margin of eyes (vs. conspicuous and very long, always surpassing the posterior margin of eyes, Figs. 4 and 21 ), lateral margin of sphenotic straight, as wide medially as anteriorly (vs.

notched, narrower medially than anteriorly, Figs. 3 and 21 ); from A. guatemalensis , from Mexico (EP) to El Salvador, by the presence of an osseous medial groove (vs. absent, Figs. 3 and 21 ), median portion of mesethmoid narrow (vs. wide, Fig. 3 ), medial notch of mesethmoid narrow and deep (vs. large and shallow, Fig. 3 ); from A. jimenezi , from Archipiélago de Las Perlas in Panama (EP), by its longer pectoral spine, 18.7–22.5 (vs. 14.6–18.1), fleshy medial groove of neurocranium conspicuous or inconspicuous, but never surpassing posterior margin of eyes (vs. conspicuous and very long, always surpassing the posterior margin of eyes, Figs. 4 and 21 ), pterotic lateral margin markedly convex, sometimes angled (vs. smoothly convex, Figs. 3 and 21 ), lateral margin of sphenotic straight, as wide medially as anteriorly (vs. notched, narrower medially than anteriorly, Figs. 3 and 21 ), external posterior branch of lateral ethmoid columnar and thin (vs. depressed and thick, Fig. 3 ), fenestra delimited by mesethmoid and lateral ethmoid conspicuous (vs. inconspicuous, Fig. 3 ); from A. seemanni , from El Salvador to Panama (EP), by its straight lateral margin of sphenotic, as wide medially as anteriorly (vs. notched, narrower medially than anteriorly, Figs. 3 and 21 ).

Description. Morphometrics and meristics summarized in Tables 2–4, 12. Head moderately long, wide and high, especially depressed at lateral ethmoid and frontal area, profile slightly elevated posteriorly, straight from mesethmoid to parietosupraoccipital. Snout rounded and moderately long. Anterior nostril rounded, with fleshy edge, posterior nostril covered by flap of skin, moderately separated and moderately distant from orbit, not connected by fleshy furrow. Eye lateral, relatively large and moderately distant to one another. Three pairs of long teretiform barbels; maxillary barbel surpassing or not membranous portion of operculum, lateral and mesial mental barbel reaching posterior margin of gill membrane. Osseous bridge formed by lateral ethmoid and frontal moderately long and slender, delimiting a fenestra little evident under the skin. Cephalic shield exposed, moderately long and moderately wide on supracleithrum, lateral ethmoid and frontal areas, with thick granulation, forming distinct patterns visible from eyes to parietosupraoccipital procces. Fleshy portion of dorsomedial groove of neurocranium, affixed to anterior cranial fontanel, moderately long and conspicuous, not surpassing eyes. Lateral margin of sphenotic straight, as wide medially as anteriorly. Pterotic lateral margin convex, sometimes angled. Parietosupraoccipital keeled, triangular, with straight lateral margins converging posteriorly, relatively short and moderately wide at posterior portion, with posterior margin convex. Nuchal plate crescent-shaped, conspicuously granulated dorsally, moderately long and narrow. Mouth subterminal, moderately large, with lips moderately thick and lower jaw arched. Vomerine tooth plates rounded. One pair of accessory tooth plates ovate, with sharp teeth. Premaxilla rectangular transversally, long and wide, with sharp teeth. Dentary with eyebrowshaped patch of teeth, separated at midline with sharp teeth. Gill membranes fused, attached to isthmus. Fourteen to 18 acicular gill rakers on first arch, 14–21 spike-shaped gill rakers on second arch and rakers present on posterior margin of all gill arches.

Body wider than its height at pectoral girdle area, progressively compressed from pectoral to caudal peduncle, ventrally flattened from pectoral girdle to anal origin. Lateral line sloping ventrally on anterior one-third, extending posteriorly to caudal peduncle, bending abruptly onto dorsal lobe of caudal. Dorsal-fin spine relatively short and thick, almost as long as pectoral-fin spine; anterior margin granulated on basal two-thirds, with weak serrations on distal third; posterior margin smooth on basal third, distal third with weak serrations. Seven dorsal-fin soft rays. Pectoral fin spine moderately long and thick; two-thirds of anterior margin weakly granulated, with weak serrations on distal third; posterior margin straight on basal one-fourth, distal three-fourths with serrations. Nine to ten pectoral-fin soft rays. Posterior process of cleithrum triangular smooth to rugose, slightly visible. Pelvic fin deep and large at base, with six rays, and well-developed fleshy protuberances in adult females. Adipose fin low, with base moderately long, shorter than anal base. Anal fin moderately high and long at base, with 18–20 rays and ventral profile convex. Caudal peduncle moderately high. Caudal-fin forked, dorsal and ventral lobes moderately long, dorsal lobe somewhat longer than ventral lobe and pointed.

Maximum length: The largest specimen examined is 330 mm TL.

Coloration in alcohol. Head and body dark brown above, whitish below; dorsal surfaces of pelvic fin proximally black, distally lighter; anal fin dark, distal tips lighter; caudal fin grayish to blackish ( Fig. 20 ).

Sexual dimorphism. Only females have well-developed fleshy protuberances or pads in basal portion of pelvic fins, especially during reproductive season. Vomerine tooth patches and acessory thooth patches not observed directly, but possibly showing same variation described for A. canteri and A. jimenezi .

Distribution and habitat. The EP Ariopsis simonsi occurs in estuarine and marine waters, from Colombia to Peru (Talará) ( Fig. 5 ).

Molecular evidence and phylogenetic relationships. Ariopsis simonsi is the sister species of a clade including A. seemanni and A. canteri ( Fig. 9 ).

Remarks. Ariopsis simonsi was described by Starks (1906) based on a single specimen collected at Callao, Peru ( Figs. 20 and 21 ). Wilson (1916) validated A. simonsi based on specimens collected at Buenaventura and Tumaco, thus broadening the geographical range of this species. In several more recent treatments, however, A.

simonsi was synonymized with A. seemanni ( Meek & Hildebrand, 1923) and Galeichthys jordani ( Hildebrand, 1946) . Hildebrand (1946) also compared two specimens collected at Cabo Blanco, Peru (290–340 mm TL), the type specimen of A. simonsi , and a specimen from Tumbes, Peru (335 mm TL), with specimens collected in Panama. The author inferred that the specimens from Peru are closer to G. jordani , than to A. seemanni , supporting his conclusions on a series of observations; e.g., “the large eye, the rather flat deep snout with nearly vertical edges, the mouth flat interorbital, which rises scarcely more than diameter of pupil above upper margin of eye, and the broad mouth, which is arched forward only slight” (see Hildebrand, 1946: 126).

The difficulty of identifying A. simonsi and differentiating it from A. seemanni results from the fact that the profile of the lateral margin of the sphenotic is the only character separating this species, which had hitherto been differentiated only by reference to combined morphometric, meristic and osteological features apparent on the type and non-type specimens. The taxonomic value of a specific osteological marker on the sphenotic has been confirmed by molecular analysis, which supports the presence of A. simonsi in Colombia and Ecuador and its differentiation from A. seemanni from Panama. (Fig, 9). A recent study of the genetic and morphological responses of ariid catfish to the transition from marine to fresh water likewise underlined the need to test seemingly slight, but constant, osteological details with molecular data ( Stange et al., 2016).

Figures

FIGURE 1. Body in lateral view. Ariopsis assimilis, Holotype, BMNH 1864.1. 26.98.

FIGURE 3. Neurocranium, dorsal view. A. Ariopsis guatemalensis, STRI 5.2.13.3.; B. A. felis, catfishesbone. acnatsci. org; C. A. canteri, uncataloged; D. A. seemanni, STRI 5.1.1.19.; E. A. jimenezi, STRI no registry; F. A. simonsi, STRI 5.1. 1.10. Abbreviation: LEepb, external posterior branch of Lateral Ethmoid; PT, Pterotic; MS, Mesethmoid; MSmn, Mesethmoid medial notch; mg, medial groove of cranium; SH, Sphenotic.

FIGURE 4. Medial groove of neurocranium. A. Ariopsis felis and B. A. assimilis. White, anterior fleshy portion (apposed to the anterior cranial fontanel); gray, posterior bony portion (formed by the mesial depression of the frontals and the anterior portion of parietosupraoccipital).

FIGURE 5. Sampling localities of examined material.

FIGURE 9. A, Clade including the genera Sciades + Potamarius + Ariopsis, extracted from the Ariidae tree of Betancur-R. et al. (2012), including five of the eight species of Ariopsis validated herein. The complete time tree was estimated using a Bayesian analysis of five mitochondrial and six nuclear gene fragments and 19 calibration points (both inside and outside Ariidae). B, Rooted RAxML phylogram with expanded specimen sampling for six species of Ariopsis, but based on the analysis of only two mitochondrial genes (Cyt b and ATPase 8 / 6; 1937 bp). Nodal numbers indicate RAxML bootstrap support values and posterior probability values (MrBayes tree), respectively. The RAxML and MrBayes trees are identical with respect to topology and highly similar with respect to branch lengths. Two letter country codes follow ISO- 3166.

FIGURE 20. Body in lateral view. Ariopsis simonsi, Holotype, USNM 53466.

FIGURE 21. Head in dorsal view. Ariopsis simonsi, Holotype, USNM 53466.