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Melanochromis auratus (Boulenger) Distribution. Unknown. Native range. Africa (Lake Malawi endemic). Remarks. No location data was provided by AFCD (2021a)., Published as part of Chan, Jeffery C. F., Tsang, Alphonse H. F., Yau, Sze-man, Hui, Tommy C. H., Lau, Anthony, Tan, Heok Hui, Low, Bi Wei, Dudgeon, David & Liew, Jia Huan, 2023, The non-native freshwater fishes of Hong Kong: diversity, distributions, and origins, pp. 128-168 in Raffles Bulletin of Zoology 71 on page 145, DOI: 10.26107/RBZ-2023-0012, http://zenodo.org/record/7815765

SUMMARY Lake Malawi (LM) cichlids have undergone heterochronic shifts in the expression of their cone opsin genes, the genes responsible for color vision. These shifts have generated species with short-, middle-, and long-wavelength-sensitive cone photoreceptors and visual systems. However, it is unclear when during the evolution of African cichlids these shifts occurred, or whether they could account for similar short- and middle-wavelength-sensitive profiles among unrelated cichlids in Lake Tanganyika (LT). To address these questions, we surveyed opsin expression in developing fry of two African cichlids, Astatotilapia burtoni from LT and Melanochromis auratus from LM. We found that A. burtoni expresses a series of three different single-cone opsins over the course of development, while M. auratus exhibits variation in the expression of only two. Neither A. burtoni nor M. auratus exhibits much variation in the expression of its double-cone opsins. These patterns reveal that A. burtoni exhibits progressive development in the sensitivity of its single-cone photoreceptors, but direct development in the sensitivity of its double-cone photoreceptors. M. auratus exhibits neotenic development in the sensitivity of both photoreceptor sets. Given the intermediate phylogenetic placement of A. burtoni between cichlids from LT and LM, our results suggest that the ancestor of LM's cichlids exhibited a progressive developmental pattern of opsin expression. These results indicate that the heterochronic shifts which produced the short- and middle-wavelength-sensitive profiles of LM's cichlids occurred recently, and suggest that the presence of similar profiles among LT's cichlids are due to parallel heterochronic shifts.

Image analysis was used to measure feeding angles of Labeotropheus trewavasae, Labeotropheus fulleborni, Melanochromis auratus, Metriaclima zebra, Petrotilapia spp., Pseudotropheus c.f. elongatus, Tropheops tropheops, and Tropheops gracilior videotaped in Lake Malawi. Petrotilapia spp. fed on vertical, slanted, and horizontal slopes, T. gracilor grazed on vertical slopes approximately 60% of the time, and the other species spent at least 80% of the time feeding on horizontal slopes. The median feeding angles ranged from 35° to 90°. There are four significantly different groups of feeding angles among the eight rock-dwelling species that were examined: (1) L. trewavasae (35°), (2) L. fulleborni, M. auratus, and P. elongatus (44.8–48.5°), (3) T. tropheops (58.4°), and (4) Petrotilapia spp., T. gracilior, and M. zebra (84.2–90.2°). Feeding angles within a species did not vary with location or differences in fish community structure. Feeding angles were associated with a combination of mouth position...

Migration rates among nine populations of the endemic Lake Malawi cichlid Melanochromis auratus were estimated along a 42-km stretch of habitat in the southern end of the lake. Allele frequencies were surveyed at four simple sequence repeat (SSR) loci. The data suggest migration rates among populations are quite low. Exact tests indicate that statistically detectable allele frequency differences exist between many adjacent populations in the study. The F ST value among all populations was estimated to be 0.151 ( P < 0.0002). A biogeographic survey suggests that the highest levels of genetic differentiation exist between populations separated by stretches of deep water. Migration is more common between populations separated by shallower water or with shoreline dispersal routes. Reduced allelic diversity was observed at more recently created habitat patches, suggesting that either bottlenecks are associated with the colonization of new habitat patches or that these shallower sites were all founded by genetically depauperate ancestral populations. The extreme philopatry of M. auratus , coupled with the patchy distribution and transient nature of its preferred habitat, provides opportunities for both selection and genetic drift to produce genetic differentiation among populations. Both processes may be important to the evolution of taxonomic diversity in the East African cichlid species flocks.

The Lake Malaŵi genus Melanochromis included five species at its inception and was originally distinguished from Pseudotropheus on the basis of morphology, including the arrangement of teeth on the lower pharyngeal bone. Thediagnosis has been extended twice, first to include all elongate mbuna that possess horizontal stripes and U-shaped toothbands and later to exclude mbuna that do not exhibit a sex-related reversal in their colour pattern. Recently, the diagnosisof the genus was refined on the basis of the melanin pattern. The genus now includes only species with a basic melaninpattern, which consists of two black horizontal lateral stripes on a light background. Most adult members of the genus,thus defined, have a sex-related reversal of pigmentation pattern. Here we describe Melanochromis mpoto n. sp. from thenorthwestern part of Lake Malawi, synonymize M. parallelus Burgess & Axelrod 1976 with M. loriae Johnson 1975,redescribe M. chipokae Johnson 1975 and M. robustus Johnson 1985, and reclassify and designate a lectotype for M. brevis Trewavas, 1935.

Melanochromis loriae Johnson 1975 (Fig. 3; Table 2) Melanochromis parallelus Burgess & Axelrod 1976 Material examined. USNM 214175, holotype, male, 100.6 mm SL, Mala&wcirc;i: Lake Mala&wcirc;i: ���Chipoka Island���, Davies et al.; USNM 215029, holotype of M. parallelus, female, 76.2 mm SL, Mala&wcirc;i: Lake Mala&wcirc;i, Axelrod, Oct. 1974; USNM 215030, paratype of M. parallelus, male, 81.5 mm SL, same collection data as USNM 215029; USNM 215031, paratypes of M. parallelus, 2, 71.7���76.6 mm SL, Mala&wcirc;i: Lake Mala&wcirc;i: obtained from aquarium dealer, 1976; PSU 6042, 10, 69.1���85.5 mm SL, Mala&wcirc;i: Lake Mala&wcirc;i: Likoma Island: 12 �� 01.62���S, 34 �� 44.16 ���E, Konings, 7 Oct. 2009. Diagnosis. Female and subadult M. loriae are distinguished from their congeners, except from those of M. melanopterus, M. lepidiadaptes, and M. kaskazini, by a white to cream coloured body (yellow to brown in other congeners), two black horizontal stripes on the flank, a black submarginal band in the dorsal fin, and black markings on the lower lobe of the caudal fin. Melanochromis loriae is distinguished from M. melanopterus and M. kaskazini by a shorter lower jaw, 31.9���35.2 %HL vs. 37.2���41.7 % in M. melanopterus and 36.4���44.6 % in M. kaskazini, and from M. lepidiadaptes by the higher number of tooth rows, 5���7 vs. 2 or 3. Male M. loriae in breeding colouration are distinguished from their congeners, except M. melanopterus, M. simulans, and M. robustus, by a broad black band in the spinous part of the dorsal fin, absent in all other congeners. Melanochromis loriae is distinguished from M. melanopterus and M. simulans by a shorter lower jaw, 31.9���35.2 %HL vs. 37.2��� 41.7 % in M. melanopterus and 40 % (Eccles, 1974) in M. simulans, and from M. robustus by a shallower caudal peduncle, 11.7���12.6 %SL vs. 12.9���14.4 %. Description. Morphometric ratios and meristic values as shown in Table 2. Small, oblong species (mean BD 35.5 % SL) with greatest body depth at about base of ninth dorsal spine. Dorsal body profile with downward curve to caudal peduncle, in some specimens more acute curvature near posterior end of dorsal fin; ventral body profile straight to slightly convex between pelvic fins and vent, with upward taper along base of anal fin to caudal peduncle. Dorsal head profile rounded, with almost continuous curve between snout tip and dorsal fin origin; horizontal eye diameter (mean 28.7 % HL) greater than preorbital depth; more than three quarters of eye (along horizontal axis) located in anterior half of head; moderate to steep head profile, straight to slightly convex snout and slightly retrognathous jaws; wide tooth bands with 5���7 rows in lower and upper jaws; teeth in outer row unequally bicuspid and teeth in inner rows tricuspid; single series of unicuspid teeth where outer and innermost rows meet. Dorsal fin with XVIII���XIX (mode XIX) spines and 7���9 (mode 8) soft rays. Anal fin with III spines and 7 or 8 (mode 7) soft rays. First 3 or 4 dorsal spines becoming gradually longer posteriorly with first spine less than �� length of fourth; last 15 spines becoming slightly longer posteriorly with last spine longest; soft dorsal with rounded (females) or rounded to subacuminate (males) tip, third or fourth ray longest, not reaching caudal fin in females and extending to approximately base of caudal fin in males. Anal spines becoming progressively longer posteriorly; third or fourth ray longest, not reaching base of caudal fin. Caudal fin subtruncate to emarginate. Pelvic fin short, not reaching anal fin. Pectoral fin rounded, paddle-shaped, short, reaching vertical line through base of 11 th or 12 th dorsal spine. Flank scales large, ctenoid; abrupt transition to small scales on breast; cheek with 4���5 (mean 5) rows of small scales; bands of small scales on proximal margins of caudal fin; 75���90 % of caudal fin covered with tiny scales; no scales on other fins. Melanochromis loriae holotype mean range Dorsal-fin spines 19 19 18���19 Dorsal-fin rays 7 8 7���9 Anal-fin spines 3 3 3 ...... continue on next page Colouration. Breeding males: head dark blue/black with two light-blue interorbital bands; cheek and gular region black; nape dark blue/black. Body dark blue/black with solid light-blue midlateral stripe and more diffuse light-blue dorso-lateral stripe; caudal peduncle dark blue/black with blue midlateral stripe; belly and breast dark blue/black. Dorsal fin dark blue with broad black submarginal band and light-blue lappets, in some males posterior dorsal with yellow margin. Caudal fin with dark-blue/black membranes and some light-blue rays, light-blue margin with narrow yellow posterior edge. Anal fin black, with 0���3 orange/yellow ocelli on posterior margin and lightblue ventral margin. Pelvic fin black with light-blue anterior margin. Pectoral fin with gray/black rays and clear membranes. Females: head gray/green on snout and nape, and cream/white on cheek and throat with two black interorbital bars and third bar on nape extending to dorso-lateral stripe. Body white/cream with broad black midlateral and dorso-lateral stripes, each 2���3 scales wide. Dorsal and anal fin white with broad black submarginal band, caudal fin white with clear margin and black spots and streaks throughout fin. Pelvic fin white with narrow white/light-blue anterior margin and black submarginal band. Pectoral fin clear. Distribution and field observations. Melanochromis loriae has a wide distribution in the northern half of the lake. The northernmost points of distribution are Mphanga Rocks, Malawi, on the west coast of the lake, and Lutara, Tanzania, on the east coast. Kande Island, Malawi and Tumbi Point, Mozambique, are the respective southernmost points of distribution (Fig. 1). This species is also found at the islands of Chizumulu and Likoma but not at Taiwanee Reef. M. loriae occurs in small numbers at most localities throughout its range, but at Ndumbi Rocks, a reef off the northwestern point of Likoma Island, it is sometimes found in foraging groups of more than 50 individuals. Besides females and non-breeding males, such groups often contain non-territorial males in full breeding colouration. The preferred habitat is mostly rocky with little sand, and the majority of individuals occur at a depth ranging between five and 20 meters (Ribbink et al. 1983). Melanochromis loriae is an omnivore, feeding mainly from the Aufwuchs on rocks. In addition to algae, however, Ribbink et al. (1983) observed cichlid fry and catfish eggs in the stomach contents of six individuals collected at Likoma Island. Melanochromis loriae is attracted to stirred-up sediment, suggesting opportunistic feeding behavior. On several occasions one of us (AK) has observed adult females of M. loriae picking fungus and anchor worms (Lernaea sp.) from larger haplochromines (non-mbuna). In all instances the afflicted fish approached the ���cleaner��� and made clear, by lying on its side or hovering in a slanting, head-up position, that it would like to have a ���treatment���. In all cases the dorsal fin was presented first. The female M. loriae then picked vigorously at the fungus or parasite and tore it off. Although this visibly hurt the ���client���, it remained in the typical position. When the cleaning process was complete, which might take more than a minute, the larger haplochromine would resume its normal swimming position and disappear. Cleaning stations, as seen in marine fishes, were not observed: after the cleaning was done the female M. loriae would disappear from the scene as well., Published as part of Konings, Adrianus F. & Stauffer, Jay R., 2012, Review of the Lake Mala��i genus Melanochromis (Teleostei: Cichlidae) with a description of a new species, pp. 1-27 in Zootaxa 3258 on pages 7-10, DOI: 10.5281/zenodo.254486, {"references":["Johnson, D. S. (1975) More new Malawi cichlids. Today's Aquarist, 2, 15 - 26.","Burgess, W. E. & Axelrod, H. R. (1976) Studies on the family Cichlidae: 4. Two new species of mbuna (rock-dwelling cichlids) from Lake Malawi. Tropical Fish Hobbyist Magazine, 24 (7), 44 - 52.","Ribbink, A. J., Marsh, B. A., Marsh, A. C., Ribbink, A. C. & Sharp, B. J. (1983) A preliminary survey of the cichlid fishes of rocky habitats in Lake Malawi. South African Journal of Zoology, 18, 149 - 310."]}

Melanochromis chipokae Johnson 1975 (Fig. 4; Table 3) Melanochromis loriae (non J ohnson) Mayland 1982; Schraml 1998 Material examined. USNM 214173, holotype, male, 87.8 mm SL, Mala&wcirc;i: Lake Mala&wcirc;i: ���Chipoka Island���, Davies et al.; PSU 6037, 3, 55.8���83.8 mm SL, Mala&wcirc;i: Lake Mala&wcirc;i: Chidunga Rocks: 13 �� 57.8 ���S, 34 �� 33.6 ���E, A. Konings, 14 Oct. 2009. Diagnosis. Females and subadults of M. chipokae are distinguished from those of all other Melanochromis species by a yellow ground colour and a black submarginal band in the dorsal and anal fins. Male M. chipokae in breeding colour have a blue occipital region, a dark-blue/black body with two wide, light-blue horizontal stripes, and a blue dorsal fin with a wide white margin. They differ from males of most Melanochromis species with a similar colour pattern, except M. robustus and M. heterochromis, by the blue occipital region that is black or gray in M. melanopterus, M. vermivorus, M. simulans, M. loriae, M. robustus, and M. mossambiquensis. Melanochromis chipokae males and females differ from M. robustus by a narrower interorbital width (17.5���23.3 %HL vs. 26.1��� 29.6 %) and from M. heterochromis by a longer lower jaw (36.5���38.9 %HL vs. 29.3���34.6 %). Description. Morphometric ratios and meristic values as shown in Table 3. Spindle-shaped species (mean BD 30.5 % SL) with greatest body depth at approximately base of fourth dorsal spine. Dorsal body profile below dorsal fin slightly convex anteriorly and with downward curve along base of soft dorsal fin to caudal peduncle; ventral body profile with gradual upward curve to anal fin and with more acute curve to caudal peduncle. Dorsal head profile straight between snout tip and interorbital, at about 30���35 �� angle relative to body axis; profile rounded between interorbital and dorsal fin origin; horizontal eye diameter (mean 29.5 % HL) much larger than preorbital depth (mean 18.2 % HL); �� to �� of eye (along horizontal axis) located in anterior half of head. Snout long with isognathous jaws; teeth on lower jaw in 3���5 rows with anteriormost teeth of outer row large, unequally bicuspid in adult males and almost equally bicuspid in females; lateral teeth unicuspid; inner row teeth small, unequally tricuspid to unicuspid in posterior rows. Dorsal fin with XVII or XVIII (mode XVIII) spines and 8 or 9 (mode 8) soft rays. Anal fin with III spines and 7 or 8 (mode 7) soft rays. First 3 or 4 dorsal spines becoming gradually longer posteriorly with first spine about �� length of third; last 14 spines becoming slightly longer posteriorly with last spine longest; soft dorsal with rounded or subacuminate tip, fifth ray longest, extending almost to base of caudal fin in females and to approximately �� length of caudal fin in males. Anal spines becoming progressively longer posteriorly; fourth or fifth ray longest, extending to approximately base of caudal fin in males, but not in females. Caudal fin subtruncate to emarginate. Pelvic fin not reaching anal fin. Pectoral fin rounded, paddle-shaped, short, posterior tip extending to vertical line through base of 10 th or 11 th dorsal spine. Flank scales large, ctenoid; abrupt transition to small scales on breast; cheek with 4 or 5 (mean 5) rows of small scales; proximal 75���90 % of caudal fin covered with tiny scales, none on dorsal or anal fin. Melanochromis chipokae holotype mean range Snout length 35.1 31.9 27.4���35.1 Postorbital head length 38.6 40.2 38.6���41.8 Horizontal eye diameter 29.7 30.1 28.0��� 32.8 ...... continue on next page Colouration. Breeding males: head below orbit dark blue/black, two light-blue interorbital bands, upper interorbital band continuous with dorso-lateral stripe on flank; occipital region blue. Body dark blue/black with solid light-blue/white midlateral stripe 2���3 scales wide and solid light-blue dorso-lateral stripe; area between dorso-lateral stripe and base of dorsal fin blue to dark blue; caudal peduncle dark blue/black with light-blue midlateral stripe; belly and breast dark blue/black. Dorsal fin blue with broad white/light-blue margin and white lappets; proximal �� to �� soft-rayed dorsal with black membranes and light-blue rays, remaining, distal part light blue. Proximal �� to �� caudal fin dark blue/black with large light-blue spot at base as continuation of mid-lateral stripe; distal �� to �� of caudal fin with light-blue rays and wide yellow margin. Anal fin black, with light-blue ventral margin and 1��� 3 orange/yellow ocelli on light-blue marginal region. Pelvic fin black with light-blue anterior edge. Pectoral fin with dark-blue/black rays and clear membranes. Females: head yellow/gray with two black interorbital bars on snout and nape; cheek and throat cream/white; two black interorbital bars, and less distinct lachrymal stripe between eye and corner of mouth; occipital region with irregular black markings blending with dorso-lateral stripe; wide black band extending from posterior edge of eye and continuing as midlateral stripe on flank. Body lemon yellow to gray-yellow; two broad black stripes on flank, midlateral stripe solid, about 3 scales wide, with feathered margins; dorso-lateral stripe wide, merging with base of dorsal fin. Dorsal and anal fins lemon yellow with black submarginal band; caudal fin gray/yellow with large black spot at base, wide lemon-yellow margin, and black spots and streaks throughout. Pelvic fin gray/yellow with white/light-blue anterior margin and wide black submarginal band. Pectoral fin with yellow rays and clear membranes. Distribution and field observations. Melanochromis chipokae is endemic to the shallow rocky reef known as Chidunga Rocks (Fig. 1). The deepest parts of the reef are about 6���7 m deep, depending on season. In general, only solitary individuals are encountered, wandering through the intermediate habitat searching for larger invertebrates and, perhaps, small fishes. Underwater observations are sporadic, and this species may be less commonly encountered than it was previously. Melanochromis chipokae may have suffered over-fishing by collectors of ornamental fishes because this species was rather common in the aquarium hobby 20 to 30 years ago (AK, pers. obs.). Territorial males have not been encountered by the authors, but males in full breeding colouration have; they proceed through the habitat at a similar speed to females and non-breeding males and rarely spend much time investigating particular items. Spawning in the lake has not been witnessed., Published as part of Konings, Adrianus F. & Stauffer, Jay R., 2012, Review of the Lake Mala��i genus Melanochromis (Teleostei: Cichlidae) with a description of a new species, pp. 1-27 in Zootaxa 3258 on pages 11-13, DOI: 10.5281/zenodo.254486, {"references":["Johnson, D. S. (1975) More new Malawi cichlids. Today's Aquarist, 2, 15 - 26.","Mayland, H. J. (1982) Der Malawi-See und seine Fische, Landbuch Verlag, Hannover, Germany, 336 pp.","Schraml, E. (1998) African cichlids I (Malawi, mbuna). Aqualog, Morfelden-Walldorf, Germany, 240 pp."]}

Melanochromis mpoto new species (Figs. 5 & 6; Table 4) Melanochromis ‘blue’ Ribbink et al. 1983 Melanochromis robustus (non Johnson) Konings 1995 Melanochromis benetos (non Bowers & Stauffer) Schraml 1998 Melanochromis spec. ‘Matema’ Schraml 1998 Holotype. PSU 6039, 86.6 mm SL, male; Mala&wcirc;i, Lake Mala&wcirc;i, Katale Island, 10 ° 27.3 ' S, 34 17.2 ' E, A. Konings, 10 Oct 2009. Paratypes. PSU 6040, 3, 66.9–91.1 mm SL, data as for holotype; PSU 6041, 7, 50.9–67.4 mm SL, Mala&wcirc;i, Lake Mala&wcirc;i, Chitande Island, 10 ° 23.8 ' S, 34 ° 15.3 ' E; A. Konings, 8 Oct 2009; BMNH 2012.1. 31.1.1, 1, 74.0 mm SL, male, data as for holotype; BMNH 2012.1. 31.1.2, 1, 53.7 mm SL, female, Mala&wcirc;i, Lake Mala&wcirc;i, Chitande Island, 10 ° 23.8 ' S, 34 ° 15.3 ' E, A. Konings, 8 Oct 2009; AMNH 255292, 1, 85.4 mm SL, male, data as for holotype; AMNH 255293, 1, 55.8 mm SL, female, Mala&wcirc;i, Lake Mala&wcirc;i, Chitande Island, 10 ° 23.8 ' S, 34 ° 15.3 ' E, A. Konings, 8 Oct 2009. Diagnosis. Females and non-breeding males of M. mpoto are distinguished from all congeners, except M. melanopterus, M. vermivorus, and M. baliodigma, by a dark brown body and a melanin pattern, when discernible, consisting of two dark horizontal stripes combined with dark vertical bars. The only other Melanochromis species with such a pattern is M. baliodigma, but M. mpoto can be distinguished from the latter species by having vertical bars that are narrower than either horizontal stripe; in M. baliodigma the vertical bars are much wider than the horizontal stripes. Mouthbrooding females of M. robustus can exhibit vertical bars as well, but this species has a greater interorbital width compared to that of M. mpoto (26.1–29.6 % HL vs. 14.8–21.8 % in M. mpoto). Melanochromis mpoto differs from M. melanopterus and M. vermivorus by a shallower cheek depth (15.4–21.7 % HL vs. 22.9–31.7 % HL in M. melanopterus and 28.2–36.2 % HL in M. vermivorus). Male M. mpoto in breeding colouration are light blue/blue without any bars or stripes visible on the flank. Melanochromis mpoto males are thus distinguished from those of most other Melanochromis species except M. lepidiadaptes, M. kaskazini, and M. wochepa. M. mpoto differs from M. wochepa males and females by its longer lower jaw (38.1–42.4 % HL vs. 26.7– 32.5 % in M. wochepa), and from M. lepidiadaptes males by the black submarginal band in its anal fin, which is entirely light blue in fully coloured males of M. lepidiadaptes. In partially coloured males of the latter species the black horizontal stripes are visible, but no vertical bars present, as is the case in M. mpoto. Males of M. mpoto differ from those of M. kaskazini by possessing more teeth in the lower jaw (18–23 vs. 10–16 in M. kaskazini), by having a shallower preorbital depth (15.4 – 20.4 % HL vs. 19.3–26.9 % in M. kaskazini), and by possessing a shallower cheek (15.4–21.7 % HL vs. 19.8 –28.0% in M. kaskazini). Fully coloured males of M. mpoto and M. kaskazini are indistinguishable on the basis of colouration alone, but the basic melanin patterns of the two species, as seen in juveniles and adult females, differ dramatically. Description. Morphometric ratios and meristic values as shown in Table 4. Medium-sized mbuna, spindleshaped body (mean BD 29.8 % SL) with greatest depth at about 9 th to 11 th dorsal spine. Dorsal body profile with gradual curve towards caudal peduncle; ventral body profile straight to slightly convex in females and convex in adult males between pelvic fins and base of rays of anal fin; posteriorly, ventral body profile gradually curving dorsally toward caudal peduncle. Dorsal head profile slightly rounded, with continuous convex curve between interorbital and dorsal-fin origin; horizontal eye diameter (mean 27.7 % HL) considerably greater than cheek depth; approximately ¾ of eye (along horizontal axis) located in anterior half of head; snout elongate and straight with isognathous jaws; tooth bands with 3–4 rows in lower and 3–5 rows in upper jaw, with noticeable gap between first and second row; teeth in anterior outer row equally to unequally bicuspid in females and unequally bicuspid to unicuspid in males; teeth in inner rows mostly unicuspid (some teeth shouldered tricuspid); single series of unicuspid teeth at junction of outer and innermost rows (Fig. 6). Lower pharyngeal bone triangular with moderate posterior indentation; few median teeth slightly enlarged but with pointed tips; other pharyngeal teeth laterally compressed with blade-like, curved tips (Fig. 6). Dorsal fin with XVII or XVIII (mode XVII) spines and 9 or 10 (mode 9) soft rays. Anal fin with III spines and 7 or 8 (mode 8) soft rays. First 4 or 5 dorsal spines becoming gradually longer posteriorly with fourth spine about twice length of first; last 12 spines becoming slightly longer posteriorly with last spine longest, about four times length of first; soft portion of dorsal fin with rounded (females) or rounded to subacuminate (males) tip, fourth or fifth ray longest, reaching base of caudal fin in females and to approximately ¼ length of caudal fin in males. Analfin spines becoming progressively longer posteriorly; fourth or fifth ray longest, reaching base of caudal fin. Caudal fin subtruncate to emarginate. Posterior tip of pelvic fin extending to approximately anal fin in females or to second or third spine of anal fin in large males. Pectoral fin paddle-shaped, posterior tip extending to vertical line through base of 11 th or 12 th dorsal spine. Flank scales large, ctenoid, with abrupt transition to small scales on breast; cheek with 5–7 (mean 6) rows of small scales; 50–75 % of caudal fin covered with tiny scales; no scales present on other fins. Melanochromis mpoto holotype mean range Snout length 34.1 32.9 29.0– 36.8 Postorbital head length 41.0 40.5 39.4 –42.0 ...... continue on next page Colouration. Breeding males: head and body cyan blue. Dorsal fin cyan blue with pale-blue distal margin and white lappets. Caudal fin cyan blue with pale-blue submarginal band and narrow yellow distal margin. Anal fin gray/blue with light-blue distal margin and 3–5 small yellow ocelli. Pelvic fin gray/blue with white/light-blue anterior margin. Pectoral fin with light-gray rays and clear membranes. Full male breeding colour conceals basic melanin pattern typical of females and juveniles. Females: head brown/dark brown with gray/brown gular region. Body bluish-brown/dark brown, often with darker midlateral and dorso-lateral stripes and vertical bars. Dorsal and caudal fins gray/brown with broad yellow posterior edge; anal fin gray/brown with 1–3 tiny yellow spots. Pelvic fin brown with narrow white/light-blue anterior margin. Pectoral fin with brown rays and gray/yellow membranes. Distribution and field observations. Melanochromis mpoto has a wide distribution in the northern part of the lake and has been encountered along the northwestern shore between Chitande Island, near Chilumba, and Nkhata Bay, and on the northeastern shore between Matema and Hongi Island, near Liuli (Fig. 1). Ribbink et al. (1983) also report this species from Likoma Island, but we have not been able to confirm this. Habitat preference and behavior of M. mpoto are similar to those of M. melanopterus in the southern part of the lake. Like the latter species, M. mpoto is a non-specialized, non-territorial cichlid, which lives in rocky and intermediate habitats. Melanochromis mpoto is most often seen at depths of 20– 40 m. It lives a predatory life but has also been seen feeding on plankton. Larger specimens appear to be mainly opportunistic piscivores. Adults are usually solitary but quick to form small “packs” of up to a dozen individuals when hunting opportunities arise. Such packs can contain more than a single male in breeding colouration. These small packs move quickly through the habitat, apparently causing commotion among small prey fishes and invertebrates, and scavenging on anything that seems worth consuming. Stomach content analyses were not performed, but small fishes (fry), invertebrates such as insect larvae, and benthic crustaceans are energetically hunted and certainly part of the diet. Hunting packs are also attracted to disturbed sediment. Territorial males have not been encountered; mouthbrooding females are solitary and sometimes found in water shallower than 10 m. Fry-guarding females have not been seen. Etymology. The specific epithet, a noun in apposition, is derived from ChiTumbuka, the language spoken along the northwestern lake shore, and means “northern,” referring to the distribution pattern of this species.

The genotypes of two microsatellite loci were determined for the mouthbrooded progeny of 13 females, representing seven species of both rock- and sand-dwelling Lake Malawi cichlid fishes. Multiple paternity is clearly demonstrated for all but two broods. One brood contained the progeny of at least six males. Heterozygosity of these two microsatellite loci in a sample of 18 male Copadichromis cyclicos was 89% and 83%, respectively. Each locus displayed 16 alleles among the 18 males. The expected average exclusion probability using both loci, given a mother/offspring pair, is 0.968, suggesting that microsatellite variation will be useful for quantifying mate choice in these taxa. The low heterozygosity of a Melanochromis auratus brood is consistent with reduced levels of mtDNA polymorphism previously documented in this species. Thus microsatellite variation may provide insight into the genetic history of these populations.

The cichlids of Lake Malawi are often considered the quintessential example of a species radiation driven primarily by sexual selection and relying on visual cues. However, the description of sound production by courting males in several species raises the possibility that acoustic signaling may play a significant role in the selection process. This study describes the mating calls from multiple species in the genera Melanochromis and Metriaclima in order to discern if there is active selection of call characteristics between closely related species or whether differences are more likely the result of drift. Variation in total call duration and fundamental frequency within genera often exceeded that between genera, particularly between the sister species Melanochromis johanni and Melanochromis cyaneorhabdos. This suggests that mating calls may indeed be subject to divergent sexual selection in closely related species. Moreover, in situ sound recordings from Lake Malawi indicate that this behavior is of ecological relevance and not simply an artifact of laboratory conditions. Together, these results suggest that current models of sexual selection in Malawian cichlids may benefit from consideration of previously ignored sensory modalities. The plasticity inherent in such multimodal processing may prove of particular importance to the species‐rich African cichlid radiation.

Difficulties in interpreting the evolutionary significance of Lake Malawi cichlid morphologies led us to examine molecular techniques for resolving relationships among closely related species. Mitochondrial DNA (mtDNA) sequence variation in the first half of the control region (445 bp) was examined within and between two species of Melanochromis, a genus of rock-dwelling cichlids from Lake Malawi, Africa. The mean number of pairwise differences observed within Melanochromis auratus (Boulenger) and Melanochromis heterochromis Bowers and Stauffer mtDNA haplotypes was 2.0 (0.45%) and 5.0 (1.13%), respectively, and a mean of 4.9 (1.11%) pairwise differences between the two species was observed. Mean pairwise differences between Melanochromis species and Pseudotropheus zebra (Boulenger), another species of rock-dwelling cichlid and Tramitichromis cf. liturus, a sand-dwelling genus, were 11.2 (2.52%) and 21.9 (4.93%), respectively. Species divergence and radiation within the genus Melanochromis appears to have occurred rapidly and recently. Mitochondrial DNA sequence variation within this genus was sufficient for generating hypotheses concerning the evolutionary relationships within the genus and for examining generic-level relationships within and among the major cichlid lineages in Lake Malawi.

Lake Malawi in eastern Africa harbors > 500 endemic species of cichlid fishes, all of which are believed to have emerged from a single founding population in the past 2 Myr. Molecular characterization of differences among the species could provide important information about the nature of speciation in the period of adaptive radiation. Because of the close relationship, however, molecular variation among the species has been difficult to ascertain. In this communication, we provide evidence for extensive differences, in major-histocompatibility-complex (Mhc) class II genes, between two related species, Pseudotropheus zebra and Melanochromis auratus. We used specific primers to amplify and sequence intron 1 and exon 2 of the class II genes from 18 individuals. Although we found 20 different sequences among the 42 that we produced, there was not a single sequence shared by the two species. Thus the study suggests that different cichlid species of Lake Malawi have different profiles of class II alleles, presumably because the polymorphism present in the ancestral founding population segregated differentially into the various species. These results make Mhc genes an important tool for elucidating speciation.

Tilapia rendalli of Lake Malawi dig large tunnels in their nests and practise communal care of young. Both these traits are considered to be antipredator adaptations.

The cichlid Melanochromis exasperatus has a natural distribution which is restricted to a single island in Lake Malawi, Africa. Diving observations indicated that it does not occur below 4.5 m depth. Measurements of depth equilibration in a pressure tank showed that males can equilibrate to a depth of 25 m and females to 18 m. Mean maximum sustained rate of depth equilibration was 2 m day−1. M. exasperatus survived a pressure decrease of 40% every 12 h from the maximum equilibration depth to the surface. The fish swim actively during the day but rest on the bottom at night when they are equilibrated to a depth 1 m deeper than ambient. Reduced activity at night is reflected in a drop in oxygen consumption to nearly half of the daytime active value.

Two questions are asked: (1) Which relation is there between the dominance hierarchy and communication? (2) Which are the dominance determining factors that are a result of group life ("group factors") and that cannot be found in pairs of animals? Melanochromis auratus, a cichlid fish from Lake Malawi, is studied under laboratory conditions as a representative model. Dominance relations in pairs of animals differ from those (between the same fishes) in groups of conspecifics. In groups M. auratus establishes and maintains a linear dominance hierarchy, of which the communicative structure is described and discussed. The number of aggressive interactions between two group members, is determined by the rank number of the actor and the reactor. Most interactions occur between rank neighbours. "Group factors" are looked for by analysing the clustering of all possible chase-interactions. Four categories of such clusterings are discussed: a preceding aggressive interaction can have an influence on high-ranked animals, the effect of such an influence is directed towards low-ranked animals. The stable hierarchy can be changed by successive circle fights. The highest-ranked group members always intervene in circle fights in order to stabilize the hierarchy, for their own benefit. This is another "group factor". An alpha animal has to spend all its energy in obtaining and maintaining its rank status. When it looses this position, it drops down the hierarchy. The benefit of the alpha place could be the reproductive succes.

The Lake Malaŵi genus Melanochromis included five species at its inception and was originally distinguished from Pseudotropheus on the basis of morphology including the arrangement of pharyngeal teeth. The diagnosis has been extended twice, first to include all elongate mbuna that possess horizontal stripes and U-shaped tooth bands and later to exclude mbuna that do not exhibit a sex-related reversal in their color pattern. We have further refined the diagnosis of the genus on the basis of the melanin pattern, resolved a longstanding dispute regarding the validity of M. heterochromis, re-evaluated the status of M. vermivorus, synonymized M. mellitus Johnson 1976 with M. melanopterus Trewavas 1935, moved M. benetos Bowers and Stauffer 1977 to Pseudotropheus, and described M. kaskazini, M. wochepa, and M. mossambiquensis from the eastern shore of the lake. Melanochromis is still paraphyletic as two species, M. joanjohnsonae Johnson 1974 and M. labrosus Trewavas 1935, are not congruent with the rest of the group, but, currently, a better alternative for these two could not be found.

The tropical freshwater fish family Cichlidae is famous for its record-breaking rates of speciation and diversity in colors and color patterns. Here, we sequenced the genome of the Lake Malawi cichlid Melanochromis auratus to study the genetic basis of an amelanistic morph of this species that lacks the typical melanic stripes and markings. Genome sequencing of the amelanistic and wild-type morph revealed the loss of the second exon of the known pigmentation gene oculocutaneous albinism II (oca2), also known as p(ink-eyed dilution) gene or melanocyte-specific transporter gene. Additional genotyping confirms the complete association with this recessive Mendelian phenotype. The deletion results in a shorter transcript, lacking an acidic di-leucine domain that is crucial for trafficking of the Oca2 protein to melanosomes. The fact that oca2 is involved in a wide range of amelanistic morphs across vertebrates demonstrates its highly conserved function.