Haplochromis latifrons, Vranken & Steenberge & Heylen & Decru & Snoeks, 2022

Vranken, Nathan, Steenberge, Maarten Van, Heylen, Annelies, Decru, Eva & Snoeks, Jos, 2022, From a pair to a dozen: the piscivorous species of Haplochromis (Cichlidae) from the Lake Edward system, European Journal of Taxonomy 815, pp. 1-94 : 14-18

Haplochromis latifrons sp. nov.

urn:lsid:zoobank.org:act:F6BB9E11-AF52-476E-87CE-5C2602859D1B

Figs 1–2 , 5–7 ; Table 1

Differential diagnosis

Species with a piscivorous morphology; body very shallow [BD 27.2–30.1 (mean 28.6) % SL]; interorbital area flat and broad [IOW 57.4–63.3 (60.0) % HW]; outer oral teeth few and large [UOT 24–42 (median 31)]; females green dorsally, white ventrally, and with a well-defined mid-lateral band; dominant male colour pattern unknown.

Amongst piscivorous species from the Lake Edward system, H. latifrons sp. nov. differs from all, except H. mentatus and H. kimondo sp. nov., by the combination of a broader interorbital area [IOW 57.4–63.3 (60.0) vs 39.3–57.1 (43.9–53.8) % HW], a shorter anal fin base [AFB 14.7–17.3 (15.7) vs 17.1–22.2 (18.0–20.5) % SL], and a smaller number of branched anal-fin rays [AFRr 7–8 vs 9–11, rarely 8].

It differs from H. mentatus by the combination of a shorter dorsal-fin base [DFB 47.2–50.1 (49.0) vs 50.3–54.2 (52.3) % SL], a strongly vs weakly prominent premaxillary pedicel, a gentler sloping lower jaw side (25–30° vs 30–45°), juveniles and females green dorsally and white ventrally vs uniformly yellow-green, and presence vs absence of a well-defined mid-lateral band.

It differs from H. kimondo sp. nov. by the combination of large vs small outer oral teeth, a smaller number of outer upper jaw teeth [UOT 24–42 (31) vs 43–70 (56)], and a shorter anal fin base [AFB 14.7–17.3 (15.7) vs 17.0–19.2 (18.0) % SL].

Etymology

Specific name from Latin ‘ latus ’ for ‘wide’ and ‘ frons ’ for ‘forehead’; referring to very broad interorbital area for a piscivorous species.

Material examined

Holotype UGANDA • ♀, 158.2 mm SL; Lake Edward ; 0°24′16.0″ S, 29°46′24.8″ E; 24 Jan. 2018; HIPE3 exped. leg.; bought at Rwenshama landing site; RMCA 2018.008.P.0330 .

Paratypes UGANDA – Lake Edward • 3 ♀♀, 122.8–134.9 mm SL; 0°12′00.0″ S, 29°47′38.4″ E; deep catch, open water ± 20 m deep; 23 Oct. 2016; HIPE1 exped. leg.; RMCA 2016.035.P.0199 to 0201 • 1 ♀, 105.4 mm SL; Rwenshama , rocky shore; 0°24′05.7″ S, 29°46′35.1″ E; 25 Mar. 2017; HIPE2 exped. leg.; RMCA 2017.006.P.0340 • 1 ♂, 82.2 mm SL; Kayanja offshore; 0°05′34.8″ S, 29°45′28.8″ E; 31 Mar. 2017; HIPE2 exped. leg.; RMCA 2017.006.P.0341 • 1 ♂, 75.3 mm SL; Kayanja offshore; 0°05′31.2″ S, 29°45′30.3″ E; 20 Jan. 2018; HIPE3 exped. leg.; RMCA 2018.008.P.0328 • 1 ♀, 155.7 mm SL; 0°24′16.0″ S, 29°46′24.8″ E; 24 Jan. 2018; HIPE3 exped. leg.; bought at Rwenshama landing site; RMCA 2018.008.P.0329 .

Description

Based on 8 specimens (75.3–158.2 mm SL); body very shallow ( Table 1 ) and oval to pyriform; caudal peduncle long ( Fig. 5 ). Head narrow, dorsally flat, and with straight dorsal outline; interorbital area flat and average in width in comparison to generalised H. elegans (but very broad for a piscivorous species); eye very small and high on head; cheek and lacrimal deep. Snout very long, acute, and slopes gently at 30–40°; premaxillary pedicel long and strongly prominent. Jaws isognathous, long, stout, very narrow, and rounded in dorsal view; gape large and slopes gently at 15–25°; maxilla (almost) extends to vertical through anterior margin of orbit. Lower jaw relatively deep and with a weakly convex ventral outline in lateral view, mental prominence absent or weakly developed, and lower jaw side nearly flat with an inclination of 25–30° to horizontal in anterior view. Upper jaw expanded anteriorly. Lips and oral mucosa large. Neurocranium shallow, ethmo-vomerine block decurved, preorbital region very shallow (19–21% NL), orbital region shallow (27–32% NL), and supraoccipital crest very shallow and pyramidical or wedge-shaped ( Fig. 6b ).

Outer oral teeth few, unicuspid, and large. Necks stout, conical, and straight; crowns recurved and acutely pointed. Dental arcades rounded. Outer teeth widely and very irregularly set with neck-distances of 1–5 neck-widths. In upper jaw, 2–3 posteriormost teeth enlarged. Inner teeth relatively large, recurved, unicuspid in large specimens (> 75 mm SL), tricuspid in small specimens (<75 mm SL). Tooth bands very slender crescent-shaped with 1–3 rows of inner teeth and narrow posteriorly until only outer row remains past ⅔ length of tooth band in upper jaw, past ½ length of tooth band in lower jaw. Inner teeth widely and irregularly set on ½–1 outer neck-width from outer row; implantation erect in first row and recumbent in subsequent rows; size decreases slightly buccally and posteriorly.

Lower pharyngeal bone long, narrow, slim, and shallow over entire length ( Fig. 7 ). Pharyngeal teeth relatively large and slender; major cusps acutely pointed; cusp gaps concave; minor cusps and cusp protuberances very small. Teeth in two median longitudinal rows equal in size and form to lateral teeth, about 10 in each row. Posterior transverse row with 15–16 teeth, implanted recumbently with lateral inclination; major cusps recurved, bluntly pointed, and laterally compressed; minor cusps small.

Chest scales small; transition to larger flank scales gradual. Minute scales on proximal half of caudal fin.

Caudal fin emarginate; dorsal and anal fins reach to vertical through 2–4 scales anterior to caudal-fin base. Pectoral and pelvic fins reach to just anterior to genital opening in females, unknown in males; first branched pelvic-fin ray slightly elongated in all specimens.

Ceratobranchial gill rakers in outer row of first gill arch short, stout, and simple; posteriormost rakers simple to trifid or anvil-shaped. Epibranchial gill rakers slender and simple.

Colouration in life

Dominant males: colour pattern unknown.

Females and juveniles: dorsal parts of body and operculum olive-green; ventral parts of body and operculum white; abrupt transition at height of lower lateral line ( Fig. 6c–d ). Flank with a well-defined black mid-lateral band from posterior margin of eye to caudal-fin base. Dorsum with a blue sheen; cheek and lower jaw white; lacrimal, snout, and lips dusky olive-green; eye with dark grey outer ring and golden inner ring. Nostril and interorbital stripes faint; lacrimal blotch large anteroventrally of eye. Pectoral fin yellowish; pelvic fin hyaline with a greenish sheen; dorsal and caudal fins uniformly dusky, dorsal fin with black lappets (i.e., distal extensions of membrane between spines); anal fin with a hyaline-white base, a dusky-yellow distal part, and 1–2 small spots resembling egg-spots.

Preserved colouration

Females and juveniles: dorsal part of body brown; ventral part of body, cheek, and lower jaw white; lacrimal, snout and lips dusky ( Fig. 6a ). Flank with a mid-lateral band from posterior margin of eye to caudal-fin base. Nostril and interorbital stripes faint, lacrimal blotch present. Pectoral fin hyaline; pelvic fin white; dorsal and caudal fins uniformly dusky, dorsal fin with black lappets; anal fin with a white base and dusky distally.

Distribution and ecology

Only known from Lake Edward, found in offshore areas. Based on its morphology, most probably a piscivorous species.

Figures

Fig. 1. The Lake Edward system, consisting of Lakes Edward and George that are connected through the Kazinga Channel. The catch localities of all examined specimens are indicated: Haplochromis sp. ‘latifrons’ (), H. mentatus Regan, 1925 (), H. sp. ‘rex’ (), H. sp. ‘simba’ (▼), H. sp. ‘glaucus’ (), H. sp. ‘aquila’ (), H. sp. ‘kimondo’ (●), H. sp. ‘falcatus’ (), H. sp. ‘curvidens’ (), H. sp. ‘pardus’ (), H. sp. ‘quasimodo’ (▲), and H. squamipinnis Regan, 1921 (█). The type localities of H. mentatus and H. squamipinnis are not shown as the exact locations are unknown.

Fig. 2. a. Differences in total number of outer teeth and premaxillary dentition between the macro- and microdontic groups of piscivores from the Lake Edward system.b. Schematic presentation of the dominant male colour patterns in life, in the various groups studied. For H. sp. ‘latifrons’ the female and for H. sp. ‘curvidens’ the non-dominant colour patterns are shown, as those of dominant males are unknown.

Fig. 5. Haplochromis latifrons sp. nov., holotype, ♀, 158.2 mm SL (RMCA 2018.008.P.0330). Drawn by N. Vranken.

Fig. 6. Haplochromis latifrons sp. nov. a. Photograph of preserved holotype (RMCA 2018.008.P.0330; 158.2 mm SL). b. X-ray image of holotype. c–d. Photographs of freshly caught specimens. c. Holotype. d. Another female (RMCA 2017.006.P.0340; 105.4 mm SL) to illustrate the live colour patterns. The contrast was slightly enhanced.

Fig. 7. Haplochromis latifrons sp. nov. (RMCA 2018.008.P.0329; 155.7 mm SL). a. Dorsal view of the lower pharyngeal jaw. b. Lateral view of the lower pharyngeal jaw.