Amphilius frieli Thomson & Page

Thomson, Alfred W., Page, Lawrence M. & Hilber, Samantha A., 2015, Revision of the Amphilius jacksonii complex (Siluriformes: Amphiliidae), with the descriptions of five new species, Zootaxa 3986 (1), pp. 61-87 : 75-78

Amphilius frieli Thomson & Page , new species

( Fig. 7 , Table 5 )

Amphilius platychir (non Günther).— Boulenger, 1920: 26, Lubumbashi à Élisabethville (MRAC P–6787) [Kafubu River system, Upper Congo basin]

Holotype. CU 97335, ex. CU 91052, Zambia, Tswishi Stream at bridge under construction, Lwela River system, 11°33'26”S, 29°09'59"E (83.1 mm SL).

Paratypes. Lwela River system: AUM 57570, ex. CU 91049 (3: 36.3–51.7); CU 91049, Zambia, Lwela River at bridge on Mansa-? road, 11°33'25”S, 29°10'10"E (21: 32–104.5); CU 91050, Zambia, Ngo Stream, about 40 km SW of Mansa, 11°31'33”S, 29°09'03"E (4: 34.2–46.8); CU 91052, same data as holotype, (11: 31.7–44.9); SAIAB 76634, same data as CU 91049 (12: 32.7–86.7); SAIAB 76789, same data as CU 91050 (5: 36.0–47.5); MRAC B3–06–P–4–6, ex. CU 91049 (3: 41.9–47.4); SAIAB 76799, same data as holotype (13: 27.3–57.2); UF 184235, ex. CU 91049 (3: 39.0–50.8).

Non-types. Chambeshi River system: CU 91056, Zambia, Kanchibiya Stream at bridge on Kasama-Mpika road, 11°29’44.2”S, 31°16'46.6"E (28: 32.5–57.0); MRAC 96031.1540–1547, Zambia, Musombizi River, trib of Chambeshi, ± 55km on the road Mbala-Kasama, ca. 09°18’S, 31°16.5'E (8: 25.8–57.8); MRAC 96031.1620–1625, Zambia, Chambeshi River, at bridge km 40 on road Mbala-Kasama, 09°12’15.3”S, 31°20'49.8"E (6: 57.7–135.6); SAIAB 40125, Zambia, Chambeshi River, rapids near Kapoloso Stream, ca. 10°43’S, 31°15'E (1: 47.8); SAIAB 46788, Zambia, Mansha River, Shiwa Hot Springs & road bridge, ca. 11°10’S, 31°35'E (16: 32.0–64.8); SAIAB 77139, Zambia, Samfa Rapids at pontoon on Chambeshsi River, 10°51’07.6”S, 31°10'02.3"E (1: 69.5); SAIAB 77142, same data as CU 91056 (28: 29.4–85.3). Kafubu River system: MRAC 6787, Democratic Republic of the Congo, Lubumbashi River, at Elisabethville [Lubumbashi], ca. 11°39’S, 27°28'E (1: 39.1); MRAC 183365–366, Democratic Republic of the Congo, at the bridge on Lubumbashi River, forested camp of the Kipopo, ca. 11°33’S, 27°22'E (2: 31.7–33.1); MRAC 183367–369, Democratic Republic of the Congo, Lubumbashi River, ± 25 km upstream of Elisabethville, ca. 11°33’S, 27°22'E (3: 33.9–39.2); MRAC 73025.0803, Democratic Republic of the Congo, Lubumbashi, in front of Lido, Lubumbashi River, ca. 11°39’S, 27°27'E (1: 118.8). Luapula River system: SAIAB 76705, Zambia, Mambilima Falls on Luapula River, 10°32’22.2”S, 28°39'40.3"E (1: 57.0). Lufira River system: MRAC 165341, Democratic Republic of the Congo, Gombela, Kafila River, Katanga, 10°46’31”S, 27°47'38"E (1: 60.8); SAIAB 77478, Democratic Republic of Congo, Diptera River near Fungurume, 10°36’20.9”S, 26°16'40.1"E (4: 43.5–77.0). Luongo River system: CU 91051, Zambia, Luongo River, below Musonda Dam, on road from Mansa to Kashiba (Route D79), 10°42’15.5”S, 28°48'03.6"E (2: 60.0–62.0); CU 91053, Zambia, Luongo River above pontoon south of Musonda Falls, Mansa-Serenje road (Route D235), 10°40’51.6”S, 28°43'09.1"E (2: 57.0–78.7); CU 91054, Zambia, Luongo River at bridge on Kashiba-Mwenda road (Route M3), 10°28’12.7”S, 31°01'28.2"E (3: 44.0–105.1); SAIAB 76663, same data as CU 91053 (3: 54.6–94.3); SAIAB 76670, same data as CU 91051 (1: 83.2); SAIAB 76729, same data as CU 91054 (5: 39.9–65.4); SAIAB 76925, Zambia, Luongo River at Mukonshi Bridge on Mwenda-Kawambwa road (Route M13), 10°08’39”S, 29°10'01.2"E (41: 32.2–53.8). Upper Congo (Lualaba) River drainage: SAIAB 81501, Democratic Republic of the Congo, Bona River [Tributary of Lac Delcommune (= Lac Nzilo)], Near Lenge Village, 10°36’34”S, 25°49'15"E (1: 78.8); SAIAB 81566, Democratic Republic of the Congo, large stream 1, Bona River system, 10°35’49”S, 25°53'23"E (1: 43.0); SAIAB 82855, Democratic Republic of the Congo, Kisanfu River, Upstream of Nayebe crossing, 10°48’01.1”S, 25°58'52.6"E (2: 46.8–85.4); SAIAB 82877, Democratic Republic of the Congo, Kisanfu River, just below bridge by hydroelectric station, 10°45’49.3”S, 25°57'49.3"E (6: 36.5–42.1); SAIAB 82898, Democratic Republic of the Congo, Kisanfu River, channel downstream of hydro station, 10°45’49.3”S, 25°57'49.3"E (6: 37.5–74.3).

Diagnosis. Diagnostic characters are summarized in Table 2 . Amphilius frieli is diagnosed from all other species of the Amphilius jacksonii complex by having more gill rakers on the first gill arch (10–11, rarely 9 or 12 vs. 6–9, rarely 5 or 10). It is further diagnosed from A. jacksonii by its deeper caudal peduncle (caudal peduncle depth 9.7–11.4% SL vs. 4.8–7.9% SL), shorter caudal peduncle (caudal peduncle 14.4–16.4% SL vs. 16.7–20.6% SL), and less slender body (body depth at anus 13.9–14.9% SL vs. 9.6–13.2% SL). It is further diagnosed from A. ruziziensis by having more branchiostegal rays (8–9 vs. 6–7), a deeper caudal peduncle (caudal peduncle depth 9.7–11.4% SL vs. 8.6–9.5% SL), shorter caudal peduncle (caudal peduncle 14.4–16.4% SL vs. 18.7–20.3% SL), and less slender body (body depth at anus 13.9–14.9% SL vs. 11.1–12.9% SL). Amphilius frieli is further diagnosed from A. pedunculus , A. crassus , and A. lujani by its narrower interorbital width (25.1–27.7% HL vs. 28.1–35.8% HL), and from A. crassus by having more branchiostegal rays (8–9 vs. 6–7, rarely 8), more branched pectoral-fin rays (9–10 vs. 7–8, rarely 9), and a shorter dorsal-fin insertion to adipose-fin insertion length (37.5–41.2% SL vs. 42.2–44.6% SL). It is further diagnosed from A. lujani by its deeper caudal peduncle (caudal peduncle depth 9.7– 11.4% SL vs. 8.1–9.5% SL), shorter caudal peduncle (caudal peduncle 14.4–16.4% SL vs. 16.8–20.9% SL).

Description. Morphometric data are in Table 5 . 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 dorsal-fin origin, then nearly horizontal to end of caudal peduncle. Greatest body depth at dorsal-fin origin. Caudal peduncle laterally compressed, with crenellated epidermal fold. Anus and urogenital openings located at midpoint of adpressed pelvic fin, closer to pelvic-fin insertionthan to origin of anal fin. Skin smooth. Lateral line complete, extending from dorsal edge of opercular cavity to caudal-fin base.

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, slightly papillate. Rictal lobe large and slightly papillate. Anterior portion of premaxillary tooth band exposed with mouth closed. Premaxillary tooth patches joined, forming crescent shaped band. 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 (25), or 9 (12) rays. Gill rakers on first epibranchial 2 (1) or 3 (37); rakers on first ceratobranchial 7 (22), or 8 (15); total gill rakers on first arch 10 (22) or 11 (15).

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 (37) rays, and fin margin straight. Pectoral fin with i,9 (37) rays; unbranched ray 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 (37) 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, deeply incised posteriorly. Caudal fin deeply forked with tips of lobes rounded; fin with i,5,6,i (36) principal rays. Anal fin with short base, origin posterior to origin of adipose-fin base, with ii,6 (2), ii,7 (2), iii,6 (24), or iii,7 (10) 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 part of adipose fin, and fifth saddle on caudal peduncle. All saddle connected laterally by broad stripe. Venter light brown with fourth and fifth saddles meeting those of opposite side. Dorsal, and anal fins light brown with dark medial band. Adipose fin dark brown to black, with anterior and posterior distal edges cream-colored. Pectoral and pelvic fins positioned horizontally with upper surfaces cream-colored with dark fin base and dark medial band. Lower surfaces light yellow. Caudal fin cream-colored with dark markings on upper and lower lobes. Caudal coloration asymmetrical, with lower lobe almost completely dark (except for small cream colored mark at base of caudal and cream-colored tip). Upper lobe with less dark pigment, with dark blotch covering dorsal edge, but caudal base with large cream-colored patch and tip cream-colored.

Distribution. Upper Congo River basin upstream of Kabalp, Democratic Republic of the Congo including tributaries of the Upper Congo mainstem, the Lufira River drainage, and the Kafubu, Chambeshi, Lwela, and Luongo River systems of the Luapula River drainage ( Fig. 6 ).

Etymology. Named for John P. Friel in recognition of his excellent contributions to the study of African fishes.

Figures

FIGURE 6. Distributions of Amphilius pedunculus (diamonds), A. frieli (dots), A. crassus (crosses) and A. lujani (squares).

FIGURE 7. Amphilius frieli, CU 97335, 83.1 mm SL, holotype; lateral, dorsal and ventral views.

Tables

TABLE 5. Morphometric data for Amphilius pedunculus. Range and mean include the holotype.

	Holotype	Range (n=20)	Mean±SD
%SL
Head length	25.6	25.4–28.0	27.1±0.7
Head width	19.8	19.8–22.2	21.1±0.6
Head height	12.5	12.1–14.1	13.5±0.5
Body depth	15.3	15.0–17.3	16.0±0.7
Body depth at anus	14.1	13.9–14.9	14.3±0.3
Predorsal length	37.2	36.2–37.8	37.2±0.6
Prepectoral length	20.4	19.7–21.3	20.6±0.5
Preanal length	72.4	71.2–73.6	72.5±0.7
Dorsal-fin base length	11.8	9.6–12.7	11.0±1.0
Adipose-fin base length	20.0	18.6–22.9	20.5±1.1
Anal-fin base length	11.6	11.5–14.3	12.6±0.8
Pelvic-fin length	18.1	17.9–19.2	18.4±0.4
Pectoral-fin length	19.2	19.2–23.5	21.8±1.0
Anal-fin length	19.1	19.0–22.3	20.2±0.9
Caudal peduncle length	15.7	14.4–16.4	16.9±0.7
Caudal peduncle depth	10.2	9.9–12.3	15.4±0.5
Anus to anal fin length	14.5	11.7–15.7	13.8±0.9
Prepelvic length	49.6	48.6–50.9	50.0±0.7
Postpelvic length	50.8	50.3–53.1	51.1±0.7
Dorsal-fin insertion to adipose	40.7	37.5–41.2	39.5±1.1
Dorsal-fin origin to caudal	66.5	63.5–66.5	64.9±0.9
Preanus length	56.3	56.4–58.7	57.7±0.8
%HL
Snout length	47.3	43.2–47.4	45.4±1.3
Interorbital distance	27.1	25.1–27.7	26.3±0.7
Maxillary barbel length	72.7	59.4–72.7	66.5±3.8
Inner mandibular barbel length	40.1	31.3–40.6	36.1±2.4
Outer mandibular barbel length	59.8	47.0–63.6	54.3±4.3
Eye diameter	13.3	12.1–16.2	14.3±1.1