Cathorops manglarensis, Alexandre P. Marceniuk, 2007

Alexandre P. Marceniuk, 2007, Description of Cathorops manglarensis, a new species from the Colombian Pacific, with redescription of Cathorops multiradiatus (Siluriformes; Ariidae)., Zootaxa 1529, pp. 33-48 : 34-39

Cathorops manglarensis , new species

(Figs. 1 and 2)

Diagnosis. Cathorops manglarensis is distinguished from all congeners through the following combination of characters: 13-16 gill rakers on first arch; 24-27 anal fin rays; dorsal fin spine shorter than pectoral fin spine; posterior margin of pectoral fin spine with shorter serrations.

This species can be further distinguished from each of the other species from the Pacific coast of Central and South America by additional characters. Cathorops manglarensis is distinguished from C. dasycephalus in lacking vomerine tooth plates (vs. vomerine tooth plates present) and an osseous bridge formed by the lateral ethmoid and frontal without granulation (vs. granulated along its entire extension). It differs from C. fuerthii by having a median groove of neurocranium deep and large, with lateral margins regular and progressively narrower posteriorly (vs. median groove narrow and shallow, with irregular margins along its entire extension), anterior nostrils closer to each other (3.6-4.8 vs. 4.9-6.0% SL), longer external mental barbel(19.7-24.4 vs. 15.9-19.7% SL), longer internal mental barbel (12.5-17.9 vs. 10.3-12.9% SL), and longer anal fin base (21.0-24.5 vs. 17.8-19.4% SL). It differs from C. hypophthalmus in possessing a shorter distance between anterior nostrils (3.6-4.8 vs. 6.9-7.1% SL) and between posterior nostrils (5.2-7.1 vs. 8.2- 8.5% SL), larger orbital diameter (3.7-4.8 vs. 3.0-3.5% SL), narrower mouth (8.8-10.5 vs. 13.1-13.2% SL) and with shorter external mental barbel (19.7-24.4 vs. 34.5-38.1% SL), internal mental barbel (12.5-17.9 vs. 26.1-31.2% SL), and dorsal fin spine (16.9-19.2 vs. 25.0-25.2% SL). Cathorops manglarensis differs from C. multiradiatus in possessing a longer maxillary barbel (28.4-38.2 vs. 22.9-27.7% SL) (fig. 3) and pectoral fin spine (18.5-22.5 vs. 16.9-18.7% SL), and longer and wider accessory tooth plates with large and numerous molariform teeth (fig. 5) (vs. shorter and narrow accessory tooth plates with small and few molariform teeth) (fig. 9). Cathorops manglarensis differs from C. tuyra in possessing a longer internal mental barbel (12.5- 17.9 vs. 8.20-12.4% SL) and pectoral fin spine (18.5-22.5 vs. 16.9-18.7% SL), shorter nuchal plate (5.0-6.8 vs. 6.8-7.5% SL), longer anal fin base (21.0-24.5 vs. 13.9-18.3% SL), deeper caudal peduncle (7.8-8.9 vs. 5.8-7.8% SL), and accessory tooth plates and dentary with moderately large molariform teeth (vs. accessory tooth plates and dentary with very large molariform teeth).

Description. (Table 1 and 2). Head moderately long and depressed, profile slightly convex at level of frontals and supraoccipital. Body wider than deeper on pectoral girdle area. Cephalic shield of moderate length granulated and visible under skin, broad around lateral ethmoid, frontal, supracleithrum and epioccipital areas. Osseous bridge formed by lateral ethmoid and frontal slender and visible under skin. Medial groove of neurocranium formed by frontals and supraoccipital very distinct, deep and large; progressively narrower posteriorly. Supraoccipital process funnel shaped short, its posterior part considerably narrower than its base, profile moderately convex. Nuchal plate half moon shaped, short and narrow. Snout round in transverse section. Anterior nostrils close to each other and posterior nostrils moderately distant among themselves. Eye lateral of moderate size. Interorbital distance moderate and distance between nostrils and orbit small. Long barbels, maxillary pair reaching half length of pectoral fin spine, external mental pair surpassing margin of gill membrane, internal pair reaching margin of gill membrane.

Mouth of moderate size, lower jaw moderately arched. Lips moderately thick, lower thicker than upper. Vomerine tooth plates absent. One pair of oval shaped accessory tooth plates large and close to one another, sometimes in contact in anterior portion. Accessory tooth plates with large molariform teeth. Premaxillary moderately long and wide. Dentary with well pronounced posterior projection, with sharp teeth on anterior portion, molariform teeth on posterior portion and some conical teeth on intermediary area. Thirteen to sixteen(15) acicular gill rakers on first arch, 5 (5) on upper limb, 8-11 (10) on lower limb. Sixteen to eighteen (17) spike-shaped gill rakers on second arch, 5-6 (5) on upper limb, 11-12 (12) on lower limb.

Ten (11) soft pectoral fin rays. Pectoral fin spine long and thick; anterior margin granulated on proximal two-thirds, distal third serrated; posterior margin straight on proximal fourth, distal three quarters with short serrations. Seven (7) soft dorsal fin rays. Dorsal fin spine short and thick, shorter than pectoral fin spine; anterior margin granulated on proximal two-thirds, distal third serrated; posterior margin serrated over almost its entire length. Six (6) pelvic fin rays, relatively high and length of base long. Adipose fin small, its base less than half as long as anal fin base. Twenty-four to twenty-seven (27) anal fin rays, deep and length of base long. Upper and lower lobes of caudal fin of moderate length, upper longer than lower. Caudal peduncle high. Lateral line reaching base of caudal-fin upper lobe.

Coloration in alcohol. Head dark brown on dorsal and lateral portions, ventrally whitish. Body with same dark brown color on dorsal portion, progressively lighter towards lateral line and whitish under lateral line, with few brown spots. Barbels dark brown. All fins dark beige overall.

Etymology. The specific epithet “manglarensis” makes reference to type-locality and life habit of the species, common in mangrove regions and estuaries from the Colombian Pacific.

Sexual dimorphism. Sexual dimorphism was observed in 5 females (89.0-195.0 mm SL) and 3 males (107.0-195.0 mm SL) with respect to the following morphological features (Table 2).

Males with larger and wider head than females, as evidenced by longer head, longer snout, greater distance between anterior and posterior nostril and orbit, greater distance between lateral horn of lateral ethmoid and external branch of supracleithrum, and wider cephalic shield on lateral ethmoid and frontal areas. Anterior portion of body relatively longer in males than in females, as evidenced by greater distance from tip of snout to pectoral and dorsal fins origin and greater distance from tip of snout to posterior margin of medial groove of neurocranium. Females have larger distance from tip of snout to pelvic fin origin and deeper body than males.

Accessory tooth plates remarkably wider in females and consequently more distant from one another in males (fig. 5). Males with smaller and fewer molariform teeth on accessory tooth plates than females (fig. 5). Accessory tooth plates totally or partially covered by epithelial tissue in males. Dentary in females with a longer posterior projection and with larger and more numerous molariform teeth on its posterior portion than males (fig. 5). Lower jaw longer in males than females and premaxillary and mouth wider in males.

Pelvic fin higher and longer in base in females than in males. Females present a larger orbital diameter, wider supraoccipital process, longer pectoral fin spine, longer lower lobe of caudal fin and relatively longer barbels than males.

Distribution. The species is described based on specimens collected in localities close to Tumaco, on the Pacific coast of Colombia (fig. 6). Apparently it is common in mangrove areas and lower portions of coastal rivers.

Material Examined. Holotype. USNM 286392 (female, 164.0 mm SL) Colombia, off Cape Manglares, south of Tumaco (01º 35' 05'' N, 79º 03' 00'' W to 01º 37' 00'' N, 79º 04' 00'' W), Oct 27 1970, Knapp, L. Paratypes. USNM 388316 (8, 164.0-195 mm SL) collected with holotype ; USNM 286388 (3, 195-195 mm SL) Colombia, off Boca San Juan, San Juan del Sur (02º 21' 00'' N 78º 39' 00'' W to 02º 23' 00'' N 78º 36' 00'' W), Oct. 20 1970, Knapp, L. ; USNM 286389 (2, 89.0-107.0 mm SL) Colombia, off Boca San Juan, north of Tumaco (02° 20' N 78° 40' W to 02° 23' N 78° 41' W), Oct 28 1970, Knapp, L. .