Ariopsis jimenezi Marceniuk, Acero, Cooke & Betancur-R, 2017, new species
Creators: name: Marceniuk, Alexandre P.
name: Acero, Arturo
name: Cooke, Richard
name: Betancur-R, Ricardo
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Siluriformes
Ariidae
Ariopsis
Ariopsis jimenezi

description: Ariopsis jimenezi, new species.
Jimenez’s sea catfish (English)
Figure 16 and 17, Tables 2–4 and 10.
Material examined. Holotype, STRI 8660 (female, 260 mm SL), Panama, Casaya Island, Archipiélago de las Perlas; Paratypes, STRI 8661 (14, 240– 302 mm SL), Panama, Casaya Island, Archipiélago de las Perlas; STRI 8662 (2, 240-258 MM SL) Panama, Casaya Island, Archipiélago de las Perlas; STRI 8127 (2, tissue 27110-27711) Panama, Casaya Island, Archipiélago de las Perlas; STRI 8566 (1, tissu 27707) Panama, Casaya Island, Archipiélago de las Perlas.
Diagnosis. Ariopsis jimenezi differs from its congeners by external posterior branch of the lateral ethmoid thick and depressed (vs. columnar and thin, Fig. 3), and an inconspicuous fenestra delimited by the mesethmoid and lateral ethmoid (vs. a conspicuous fenestra, Fig. 3). The species can be further differentiated as follows: from A. assimilis, from Mexico (Quintana Roo) to Honduras (Caribbean), by shorter pectoral spine 14.6–18.1% SL (vs. 18.2–22.6% SL), osseous medial groove present (vs. absent; Figs. 3 and 17), fleshy medial groove of neurocranium conspicuous and very long, always surpassing the posterior margin of eyes (vs. conspicuous or inconspicuous, but never surpassing posterior margin of eyes, Figs. 4 and 17), lateral margin of sphenotic notched, narrower medially than anteriorly (vs. straight, as wide medially as anteriorly, Figs. 3 and 17); margin of pterotic smoothly convex (vs. markedly convex, sometimes angled, Figs. 3 and 17); from A. canteri, from Colombian Caribbean, osseous medial groove present (vs. absent; Figs. 3 and 17), lateral margin of sphenotic notched, narrower medially than anteriorly (vs. straight, as wide medially as anteriorly, Figs. 3 and 17), pterotic lateral margin smoothly convex (vs. markedly convex, sometimes angled, Figs. 3 and 17); from A. felis, from Massachusetts (US) to Yucatán in Mexico (Caribbean), by the presence of 16–17 gill rakers on the first gill arch, rarely 15 (vs. 13–15, rarely 16, Table 3); from A. gilberti, from Mexico (EP), by 29–34 gill rakers on the first and second gill arches (vs. 40–42), pterotic lateral margin smoothly convex (vs. markedly convex, sometimes angled, Figs. 3 and 17); from A. guatemalensis, from Mexico to Costa Rica (EP), by its narrower mouth 9.0–11.4% SL (vs. 13.0–15.2% SL); narrower distance between anterior nostrils 5.6–6.5% SL (vs. 7.1–8.6% SL); shorter pectoral spine 14.6–18.1% SL (vs. 18.2–20.5% SL), osseous medial groove present (vs. absent; Figs. 3 and 17), fleshy medial groove of neurocranium conspicuous and very long, always surpassing the posterior margin of eyes (vs. conspicuous or inconspicuous, but never surpassing posterior margin of eyes, Figs. 4 and 17), lateral margin of sphenotic notched, narrower medially than anteriorly (vs. straight, as wide medially as anteriorly, Figs. 3 and 17), median portion of mesethmoid narrow (vs. wide, Figs. 3 and 17), medial notch of mesethmoid narrow and deep (vs. large and shallow, Figs. 3 and 17); from A. seemanni, from El Salvador to Panama (EP), by fleshy medial groove of neurocranium conspicuous and very long, always surpassing the posterior margin of eyes (vs. conspicuous or inconspicuous, but never surpassing posterior margin of eyes, Figs. 4 and 17), pterotic lateral margin smoothly convex (vs. markedly convex, sometimes angled, Figs. 3 and 17); from A. simonsi, from Colombia to Peru (EP), by fleshy medial groove of neurocranium conspicuous and very long, always surpassing the posterior margin of eyes (vs. conspicuous or inconspicuous, but never surpassing posterior margin of eyes, Figs. 4 and 17), lateral margin of sphenotic notched, narrower medially than anteriorly (vs. straight, as wide medially as anteriorly, Figs. 3 and 17), pterotic lateral margin smoothly convex (vs. markedly convex, sometimes angled, Figs. 3 and 17).
Description. Morphometrics and meristics summarized in Tables 2–4, 10. 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 distant to one another and moderately distant to orbit, not connected by fleshy furrow. Eye lateral, relatively small. Eyes well separated. Three pairs of long teretiform barbels; maxillary barbel surpassing or not membranous portion of opercle, lateral and mesial mental barbel not reaching posterior margin of gill membrane. Osseous bridge formed by lateral ethmoid very short and very thick, delimiting a fenestra not evident under the skin. Cephalic shield exposed, moderately long and relatively narrow on supracleithrum area, and wider on lateral ethmoid and frontal areas, with thick granulation, sparse and especially visible on sphenotic and parietosupraoccipital. Fleshy portion of dorsomedial groove of neurocranium, affixed to anterior cranial fontanel, long and conspicuous, reaching eyes. Lateral margin of sphenotic notched, narrower medially than anteriorly. Pterotic lateral margin smoothly convex. Parietosupraoccipital keeled, triangular, with straight lateral margins converging posteriorly, relatively long and moderately wide at posterior portion, with posterior margin convex. Nuchal plate crescent-shaped, conspicuously granulated dorsally, relatively long and wide. 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 eyebrow-shaped patch of teeth, separated at midline with sharp teeth. Gill membranes fused, attached to isthmus. Fifteen to 17 acicular gill rakers on first arch, 14–17 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 spine relatively short and thick, shorter than pectoral 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 females. Adipose-fin low, with base moderately long, shorter than anal base. Anal fin moderately high and long at base, with 16–19 rays and ventral profile convex. Caudal peduncle moderately high. Caudal-fin forked, dorsal and vetral lobes relatively long, dorsal lobe somewhat longer than ventral lobe, slightly pointed.
Maximum length: Grows to about 350 mm TL.
Coloration in alcohol. Head and body dark brown above, whitish below; dorsal surfaces of pelvic proximally black, distally lighter; anal dark, distal tips lighter; caudal grayish to blackish (Fig. 16).
Sexual dimorphism. Only females have well-developed fleshy protuberances or pads, in basal portion of pelvics, especially during reproductive season. Vomerine tooth patches ovate to square in females, and reduced and transversally elongated in males. In females, accessory tooth patches larger and ovate (relatively smaller and elongated in males).
Distribution and habitat. Ariopsis jimenezi is only known from Archipiélago de Las Perlas in Panama (EP). It occurs in shallow inshore marine waters (Fig. 5).
Molecular evidence and phylogenetic relationships. Ariopsis jimenezi is the sister species of a clade including A. simonsi, A. seemanni and A. canteri (Fig. 9).
Etymology. The species is named after Máximo Jiménez Acosta, zooarchaeology technician at the Smithsonian Tropical Research Institute, Panama, who drew attention to the possible existence of a new species based on the examination of osteological characters in specimens formerly missidentified as A. seemanni.
Remarks. The new species is recognized based on a combination of meristic and morphometric features as well as on unique osteological characters. Notably, the depressed and thick external posterior branch of the lateral ethmoid and the inconspicuous fenestra (delimited by mesethmoid and lateral ethmoid) are recognized as derived states (autapomorphies) within a phylogenetic framework of Ariopsis (see Marceniuk, et al. 2012b; Marceniuk & Betancur-R, in preparation).
description: Published as part of 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, pp. 1-42 in Zootaxa 4290 (1) on pages 27-31, DOI: 10.11646/zootaxa.4290.1.1, http://zenodo.org/record/828843