Mylochromis durophagus, Turner, 2025

Turner, George F., 2025, Two new species of Mylochromis (Cichlidae) from Lake Malawi, Africa, Journal of Fish Biology 106 (4), pp. 1124-1133 : 1128-1130

3.2 | Mylochromis durophagus new species urn:lsid:zoobank.org:pub:B29807EB-60A6-4389-A235-993B72E39C9B .

Holotype: University Museum of Zoology , Cambridge: UMZC 2016.18 .13, apparent male, 89.7 mm SL, collected by scuba at Nkhata Bay February 20, 2016, by Malawi Cichlid Genomic Diversity Survey ( MCGDS) (Figures 5 – 8).

Paratypes (2): UMZC 2016.18 .15, apparent female, 67.5 mm SL, collected with holotype and one female UMZC 2016.25 .2, 80.0 mm SL collected by scuba at Mphanga Rocks , Chilumba, February 23, 2016, by Malawi Cichlid Genomic Diversity Survey ( MCGDS) .

Etymology: “duro-” = from durus, Latin, meaning “hard” + “-phagus” = Latin, meaning “to eat,” referring to the presumed diet of hard-shelled invertebrates indicated by the molariform pharyngeal dentition.

Diagnosis: the lower jaw dentition is “ Placidochromis -type,” with the outer series extending in a relatively straight line toward the posterior end of the jaw. This and the strong oblique stripe and lack of specialized morphology characterize the species as a member of the F I G U R E 7 Mylochromis durophagus : jaw teeth of holotype

(left) and lower pharyngeal bone of

80 mm paratype UMZC 2016.25.2. genus Mylochromis . The strongly molarized pharyngeal dentition distinguishes the species from all other known Mylochromis , except M. anaphyrmus , M. mola , and M. sphaerodon (Figure 9). M. mola differs by having a long snout (36.3% – 40.3% vs. 33.4% – 37.4% HL in M. durophagus ), more acutely pointed head profile, more slender body (body depth 34.5% – 37.1% vs. 39.1% – 40.2% SL vs. in M. durophagus ), and a blotchy, interrupted oblique stripe. M. durophagus has a much less steep head profile than M. anaphyrmus (40 vs. 56 – 67) and a more upwardly angled gape (40 vs. 10 – 20). M. durophagus also has a less steep head profile than M. sphaerodon (40 vs. 50 – 52).

Description: body measurements and counts are presented in Table 2. M. durophagus is a medium-sized (<90 mm SL), laterally compressed (maximum body depth 2.35 – 2.42 times maximum width) cichlid fish with a rounded head profile, terminal mouth, and large eyes (29.3% – 33.1% HL). Prominent, broad continuous oblique stripe on flanks, narrowing anteriorly (Figures 5 and 6).

All specimens are moderately deep bodied and laterally compressed, with deepest part of body generally around first to fifth dorsal-fin spine. Anterior upper lateral profile moderately convex, straight, angled about 40 to horizontal, from tip of snout to above eye, with little or no obvious bulge made by premaxillary pedicel, then curving gently to first dorsal spine. Jaws isognathous to slightly retrognathous, jaw teeth not prominent when mouth closed. Tip of snout well above level of upper insertion of pectoral fin and about level with the bottom of eye or slightly above. Lower profile curves from lower jaw tip to insertion of pelvic fins, then almost straight from pelvics to first anal spine. Mouth relatively small, gape angled about 40 to horizontal. Lips moderately fleshy in larger specimens, relatively thin in smallest. Posterior end of maxilla well in front of anterior margin of eye. Eye large, circular, and just below the head profile in lateral view. Lachrymal squarish with five openings.

Flank scales weakly ctenoid, with cteni becoming reduced dorsally, particularly anteriorly above upper lateral line, where they transition into a cycloid state. Scales on chest relatively large. Gradual transition in size from larger flank scales, as is typical in non-mbuna Malawian endemic haplochromines ( Eccles & Trewavas, 1989). Caudal fin densely scaled, over at least proximal three-fourths.

Cephalic lateral-line pores fairly inconspicuous, and flank lateral line shows usual cichlid pattern of separate upper and lower portions, with up to four pored scales after kink in upper lateral line and one to three smaller pored scales after line of flexion of hypurals.

Pectoral fins relatively long, to around vertical plane through third anal spine, whereas pelvics occasionally just reach first anal spine base. Filaments of dorsal and anal fins reaching just past base of caudal fin in larger specimens, but well short in smallest. Caudal fin emarginate.

Lower jaw bones relatively slight and lacking a mental process. Outer series of teeth in lower jaw stout, erect, prominent, and deeply implanted, bicuspid with pointed, obliquely truncated major cusps. Upper jaw outer series similar, but both cusps more rounded, larger becoming more pointed posteriorly. In both upper and lower jaws, inner teeth very small, scattered, not forming clear rows.

Lower pharyngeal bone heavily built with hemispherical molariform teeth central-posteriorly. Gill rakers widely spaced, thick, blunt.

Female beige, paler on chest and belly, with a strong oblique stripe from nape to the caudal fin base, extending into fin rays. Dorsal fin has dull orange spots in two rows on spinous membranes, three oblique rows in soft dorsal; lappets dark in spinous portion. Caudal, anal, and pelvic fins dusky, pectorals yellowish. Mature male darker with golden spots on majority of flank scales. Dorsal, caudal, anal, and pelvic fins dark, dorsal and caudal with numerous orange spots. Dorsal-fin lappets white with orange tips. Dark lachrymal stripe visible. Based on other Malawian haplochromines, this is unlikely to be full male breeding dress.

Distribution and ecology: known only from two specimens collected from rocky shores at Nkhata Bay and one at Mphanga Rocks near Chilumba in the northwestern part of Lake Malawi. All were collected in shallow water by scuba divers.