Starks, 1906 :764 Ariopsis seemanni Chirichigno & Cornejo, 2001 : 18 simonsi A. seemanni ( Meek & Hildebrand, 1923 ) Galeichthys jordani ( Hildebrand, 1946 ) A. simonsi G. jordani A. seemanni A. simonsi A. seemanni A. simonsi A. seemanni Taxonomic revision of the New World genus Ariopsis Gill (Siluriformes: Ariidae), with description of two new species Marceniuk, Alexandre P. Acero, Arturo Cooke, Richard Betancur-R, Ricardo Zootaxa 2017 4290 1 1 42 3F3FX Starks, 1906 Starks 1906 [151,530,1663,1690] Actinopterygii Ariidae Ariopsis Animalia Siluriformes 34 35 Chordata species simonsi   Figures 20and 21, Tables 2–4and 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.  USNM53466( 1, 215 mmSl), Peru, Callao.   USNM284549(3, 88– 117 mmSl) Peru, Tumbes, Lower Rio Tumbes, NE Ar Las Paralles. Nontype-specimens.  AUM57436 (1, 92 mm Sl), Peru, Lima;  INV  PEC6718(2, 183– 210 mmSL), Colombia,  Valledel Cauca, Buenaventura, LaBarra-Juanchaco- Ladrilleros( 4° 1' 0" N, 77° 28' 0" W), trawl,  3.4 m, Biomálaga.  INV  PEC9087(3, 183– 245 mmSL),  Valledel Cauca, Mercado de Buenaventura, A. Acero P., 1999. Discarded Material: (7, 185– 274 mmSL),  Valledel Cauca, Mercado de Buenaventura,  1998–2006.   Diagnosis.  Ariopsis simonsidiffers 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. 3and 21); from  A. canteri, from Colombian Caribbean, the presence of an osseous medial groove ( vs.absent; Figs. 3and 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. 4and 21), pterotic lateral margin convex, sometimes angled ( vs.smoothly convex, Figs. 3and 21), lateral margin of sphenotic straight, as wide medially as anteriorly ( vs.notched, narrower medially than anteriorly, Figs. 3and 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. 4and 21), lateral margin of sphenotic straight, as wide medially as anteriorly ( vs. notched, narrower medially than anteriorly, Figs. 3and 21); from  A. guatemalensis, from  Mexico(EP) to El Salvador, by the presence of an osseous medial groove ( vs.absent, Figs. 3and 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. 4and 21), pterotic lateral margin markedly convex, sometimes angled ( vs.smoothly convex, Figs. 3and 21), lateral margin of sphenotic straight, as wide medially as anteriorly ( vs.notched, narrower medially than anteriorly, Figs. 3and 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 Salvadorto  Panama(EP), by its straight lateral margin of sphenotic, as wide medially as anteriorly ( vs.notched, narrower medially than anteriorly, Figs. 3and 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 mmTL.  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. canteriand  A. jimenezi.   Distribution and habitat.The EP  Ariopsis simonsioccurs in estuarine and marine waters, from Colombiato Peru(Talará) ( Fig. 5).   TABLE 12.Morphometric data for  Ariopsis simonsi. Standard length is expressed in millimeters and all other measurements are expressed in percents of standard length.    Holotype  N Mean Range  Standard length (mm) 215.9 16 88–274  Head length 27.7 16 26.3 23.5–30.6  Snout length 7.8 15 6.4 5.4–7.0  Distance between anterior nostrils 7.2 16 5.8 5.1–6.6  Distance between posterior nostrils 6.5 16 6.1 5.1–6.6  Orbital diameter 5.3 16 5.3 4.2–6.7  Interorbital distance 15.2 16 12.5 11.3–13.7  Maxillary barbel length 24.6 14 26.2 21.6–34.0  Lateral mental barbel length 18.4 16 16.7 11.7–21.8  Mesial mental barbel length 10.3 16 10.0 8.0–12.5  Mouth width 13.1 16 10.3 8.9–11.2  Width of cephalic shield at lateral ethmoid area 14.9 16 13.4 11.6–14.8  Width of cephalic shield at frontals area 10.9 16 9.7 8.7–11.0  Width of cephalic shield at supracleithrum area 19.3 16 18.2 16.9–19.6  Parietosupraoccipital process length  Parietosupraoccipital process width  Nuchal-plate length 5.9  Nuchal-plate width 7.6  Body depth 16 18.7 15.4–21.9  Body width 16 20.0 18.4–21.1  Distance from snout to pectoral fin 16 21.2 19.6–24.2  Distance from snout to dorsal fin 16 34.1 30.7–36.0  Distance from snout to pelvic fin 16 52.5 50.4–55.1  Distance from snout to adipose fin 16 74.2 69.2–76.6  Distance from snout to anal fin 16 69.9 65.8–72.5  Caudal-peduncle height 7.7 16 7.3 6.5–8.6  Pectoral-fin spine length 18.7 4 21.5 20.1–22.5  Dorsal-fin spine length 18.2 4 22.1 20.6–22.9  Pelvic-fin base length 5.0 16 4.5 3.2–6.0  Pelvic-fin height 14.6 15 17.6 14.4–21.3  Adipose-fin base length 16 8.6 6.5–11.3  Adipose-fin height  Anal-fin base length 16 14.2 12.3–16.3  Anal-fin height  Caudal-fin upper lobe length  Caudal-fin lower lobe length  Molecular evidence and phylogenetic relationships.  Ariopsis simonsiis the sister species of a clade including  A. seemanniand  A. canteri( Fig. 9).   Remarks.  Ariopsis simonsiwas described by Starks (1906)based on a single specimen collected at Callao, Peru( Figs. 20and 21). Wilson (1916)validated  A. simonsibased on specimens collected at Buenaventura and Tumaco, thus broadening the geographical range of this species. In several more recent treatments, however, A.    simonsiwas 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 mmTL), the type specimen of  A. simonsi, and a specimen from Tumbes, Peru ( 335 mmTL), 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. simonsiand differentiating it from  A. seemanniresults 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. simonsiin Colombia and Ecuador and its differentiation from  A. seemannifrom 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). 1572325489 [151,1077,1940,1965] USNM Peru Callao 34 35 USNM 53466 1 Callao 1572325474 USNM NE Ar Las Paralles. Non Peru Tumbes 34 35 USNM 284549 1 Tumbes 1572325484 AUM Peru 35 36 Lima 34 35 1 Lima 1572325488 INV, PEC Buenaventura & La & Ladrilleros & Biomalaga Colombia 3 4.016667 Valle del Cauca 21 -77.46667 35 36 PEC6718 1 Valle del Cauca 1572325483 1998 2006 1998 INV, PEC Mercado de Buenaventura, A. & Acero P. & Discarded Material & Mercado de Buenaventura Colombia Valle del Cauca 35 36 PEC9087 1 Valle del Cauca