Amphilius pagei Thomson & Swartz, 2018

Thomson, Alfred W. & Swartz, Ernst R., 2018, A new species catfish, Amphilius pagei (Siluriformes: Amphiliidae) from Angola, Zootaxa 4420 (2), pp. 292-300 : 293-297

Amphilius pagei Thomson & Swartz , new species

( Fig. 1 ; Tables 1 & 2)

Holotype. SAIAB 85158 , Angola, just above Calema falls , Cuanza River basin, 9°53’28.2"S, 16°18'25.8"E (1: 141.6)

Paratypes. Cuanza River basin: BMNH 2018.3.13.1–2, ex . SAIAB 85100 (2: 39.3–93.1); MRAC 2017.024.P.0001-0002, ex. SAIAB 85100 (2: 45.9–89.5); SAIAB 85043 , Angola, Northern track between Tchuimbo and Kutato , 12°16’37"S, 16°21'02"E (1: 99.9) ; SAIAB 85058 , Angola, Bridge between Huambo & Kuito , 12°28’14"S, 16°49'26"E (3: 40.7–92.7) ; SAIAB 85100 , Angola, Lucala 1 bridge, 09°16’08"S, 15°14'49"E (9: 33.9–95.8) ; SAIAB 85114, same locality as SAIAB 85100 ; SAIAB 85119 , Angola, Above Calandula Falls: Immediately above the major waterfall, 09°04’26"S, 16°00'00"E (1: 49.5) ; SAIAB 85136 , Angola, Below Calandula Falls ; below the major waterfall, 09°04’37"S, 15°59'59"E (2: 63.4–100.0); UF 239296, ex . SAIAB 85100 (3: 39.4–84.8).

Non-Types. Kasai River drainage, Congo River basin: MRAC 162351 , Angola, Kwango River system, Cuango River , Cafunfo , ca. 08°46’59"S, 18°01'59"E (8: 61.1–128.4) ; MRAC 78006.1055 , Angola, Kwango River system, Cafunfo, Tshingando River , ca. 08°46’59"S, 18°01'59"E (5: 85.2–108.6) ; MRAC 78006.1060 , Angola, Kwango River system, Cafunfo, Borio 2, ca. 08°45’00"S, 18°04'59"E (10: 72.3–90.9) ; MRAC 78006.1072 , Angola, Kwango River system, Cuango near Tumbica mine, ca. 08°48’31"S, 17°59'16"E (1: 84.1).

Diagnosis. Amphilius pagei is distinguished from all other species of Amphilius by the following combination of characters: presence (vs. absence) of an epidermal fold at the base of the caudal fin, 6+7 (i,5,6,i) principal caudal-fin rays (vs. 7+8 or 8+9), a variably mottled body coloration that includes dark saddles (vs. body coloration not mottled with dark saddles), head and body heavily spotted (vs. head and body not heavily spotted), epidermal fold smooth (vs. crenelations present on epidermal fold), branchiostegal rays usually eight or nine, and total gill rakers usually 12–16.

Amphilius pagei differs from all High African Amphilius species ( A. athiensis , A. chalei , A. cryptobullatus , A. grandis , A. kivuensis , A. krefftii , A. lampei , A. natalensis , A. uranoscopus , and A. zairensis ), by the presence (vs. absence) of an epidermal fold at the base of the caudal fin and 6+7 (i,5,6,i) principal caudal-fin rays (vs. 8+9). It differs from all Low African species ( A. brevis , A. caudosignatus , A. dimonikensis , A. grammatophorus , A. kakrimensis , A. korupi , A. lamani , A. longirostris , A. maesii , A. mamonekenensis , A. nigricaudatus , A. opisthophthalmus , A. pulcher ) except A. atesuensis , A. lentiginosus , A. rheophilus , and species of the A. jacksonii complex (sensu Thomson et al. 2015), by its variably mottled body coloration that includes dark saddles (vs. body coloration not mottled with dark saddles) and differs from all Low African species except A. lentiginosus and the A. jacksonii complex by having more total gill rakers on the first gill arch (12–16, vs. five to 11). It differs from species of the A. jacksonii complex by having its head and body heavily spotted (vs. head and body not heavily spotted) and by having more total gill rakers on the first gill arch (12–16, vs. six to 11, rarely five or 12). Amphilius pagei differs from A. longirostris and A. opisthophthalmus by having 6+7 (i,5,6,i) principal caudal-fin rays (vs. 7+8) and a well-developed epidermal fold (vs. fold rudimentary) and is further diagnosed from A. atesuensis , A. caudosignatus , A. grammatophorus , A. kakrimensis , A. lamani , A. lentiginosus , A. mamonekenensis , A. nigricaudatus , A. platychir , A. pulcher and A. rheophilus by having a smooth epidermal fold (vs. epidermal fold with distinct crenelations). If differs from A. brevis , A. caudosignatus , A. dimonikensis , A. korupi , A. lamani , A. maesii , A. mamonekenensis , and A. nigricaudatus by having fewer branchiostegal rays (eight or nine vs. 10 or more) and differs from A. lentiginosus and A. rheophilus by having a greater number of branchiostegal rays (eight or nine vs. six or seven).

Description. Morphometric data as in Table 1. Body elongate, ventral profile flattened ventrally to anal-fin base, then tapered dorsally to end of caudal peduncle. Dorsal profile rising gently from tip of snout to origin of dorsal fin, then nearly horizontal to end of caudal peduncle. Greatest body depth at dorsal-fin origin. Caudal peduncle laterally compressed, with smooth epidermal fold. Anus and urogenital openings located at midpoint extent of pelvic fin, closer to insertion of pelvic fin than to origin of anal fin. Skin smooth. Lateral line complete, extending from dorsal edge of opercular cavity to base of caudal fin.

Head and anterior part of body depressed and broad. Head wedge-shaped in lateral view. Snout broad, blunt when viewed from above. Head becoming wider from tip of snout to pectoral-fin base. Branchiostegal membranes moderately joined at isthmus forming a V -shaped connection.

Mouth broad, gently curved, subterminal. Lips moderately fleshy, papillate. Rictal lobe large and papillate. Anterior portion of premaxillary tooth band exposed with mouth closed. Premaxillary tooth patches joined, forming U -shaped band with anterior broad protrusion. Premaxillary and dentary teeth short, conical. Dentary tooth patches forming U -shaped band, separated medially.

Three pairs of simple, tapered circumoral barbels. Maxillary barbel large, fleshy and flattened with pointed tip; barbel extending posterolaterally from corner of mouth to pectoral-fin base. Outer mandibular barbel thin with pointed tip, origin at posterior corner of lower jaw, extending to origin of pectoral-fin. Inner mandibular barbel originates anterolaterally of inner mandibular barbel, extending to edge of branchiostegal membrane. Branchiostegal membrane with 8* (6), or 9 (10) rays. Gill rakers on first epibranchial 3 (3), 4* (13) or 5 (1); rakers on first ceratobranchial 9 (5), 10 (5), 11* (5) or 12 (2); total gill rakers on first arch 12 (2), 13 (4), 14 (4), 15* (4), or 16 (3).

Eye small, positioned dorsolaterally approximately midway between tip of snout and posterior margin of operculum. Horizontal diameter of eye slightly wider than vertical diameter. Eye without free orbit; covered with skin confluent with dorsal surface of head. Anterior and posterior nares with prominent tubular rims; nares separate but relatively close to each other. Posterior nare located about midway between eye and tip of snout.

Dorsal-fin origin at point over tip of pectoral fin. Dorsal fin with i,6 (17) rays, and fin margin straight. Pectoral fin with i,9 (17) rays with first ray unbranched and greatly thickened. Pectoral fin with four or five innermost rays progressively shorter making posterior fin margin rounded. Origin of pelvic fin posterior of dorsal-fin insertion. Pelvic fin with i,5 (17) rays with first ray unbranched and greatly thickened. Pelvic fin with straight posterior margin.

Adipose-fin base longer than anal-fin base, origin anterior to origin of anal-fin base, fin extending past anal-fin insertion. Margin strongly convex with sharply rounded edge, not deeply incised posteriorly. Caudal fin forked with tips of lobes rounded; fin with i,5,6,i (17) principal rays. Anal fin with short base, origin posterior to origin of adipose-fin base, with ii,5* (16) or ii,6 (1) rays. Anal fin margin almost straight.

Coloration. Body variably mottled with dark saddles. First saddle posterior of head, second saddle at dorsal fin, third saddle between dorsal and adipose fins, fourth saddle under anterior of adipose fin, and fifth saddle on caudal peduncle. All saddle connected laterally by broad stripe. Body and head covered with small dark spots, but spots isolated to dark pigmented areas. Spots also present on pigmented areas of all fins. Ventral region light brown with fourth and fifth saddles extending around ventral side. Dorsal and anal fins light brown. Dorsal and anal fins dark at base with dark medial bands. On large specimens, medial band extends to distal edge. Adipose fin dark brown, cream colored distally pectoral and pelvic fins positioned horizontally with upper surfaces brown and lower surfaces light yellow. Each with dark medial band. Caudal fin brown with medial cream patch and tips of upper and lower lobes cream. Caudal coloration asymmetrical, lower lobe more greatly covered with pigment than upper lobe.

Distribution. Known from the Cuanza River basin and Kwango River system, Kasai River drainage, Congo basin, Angola ( Fig. 2 ).

Etymology. Named for Larry M. Page in recognition of his excellent contributions to the study of freshwater fishes.

Figures

FIGURE 1. Lateral, dorsal and ventral views of the holotype of Amphilius pagei, SAIAB 85158, 141.6 mm SL, Cuanza River basin, Angola. Scale bar equals 1 cm.

FIGURE 2. Distributions of Amphilius pagei and Amphilius lentiginosus.