Review of the Lake Malaŵi genus Melanochromis (Teleostei: Cichlidae) with a description of a new species
Author
Konings, Adrianus F.
Author
Stauffer, Jay R.
text
Zootaxa
2012
3258
1
27
journal article
10.5281/zenodo.254486
747735bb-a251-4624-a513-e84ef2407e37
1175-5326
254486
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;
Malaŵi
, Lake
Malaŵi
, Katale Island,
10° 27.3' S
,
34 17.2' E
, A. Konings,
10 Oct 2009
.
FIGURE 5.
A.
Melanochromis mpoto
, holotype, PSU 6039, 86.6 mm SL, male; MalaŴi, Lake MalaŴi, Katale Island, A. Konings, 10 Oct 2009; B.
M. mpoto
, male in breeding colouration (approx. 80 mm SL) at Chitande Island, Lake MalaŴi, MalaŴi; C.
M. mpoto
, female (approx. 50 mm SL) at Katale Island, Lake MalaŴi, MalaŴi.
Paratypes
.
PSU
6040, 3,
66.9–91.1 mm
SL, data as for
holotype
;
PSU
6041, 7,
50.9–67.4 mm
SL,
Malaŵi
, Lake
Malaŵi
, 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,
Malaŵi
, Lake
Malaŵi
, 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,
Malaŵi
, Lake
Malaŵi
, 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.
FIGURE 6.
Melanochromis mpoto
, PSU 10568, 79 mm SL, MalaŴi, Lake MalaŴi, Luwino Reef, 10° 26.88’S, 34° 16.97’E; A. latero-dorsal view of dentary; B. latero-dorsal view of lower pharyngeal jaw.
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 9th to 11th 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 11th or 12th 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.
TABLE 4.
Morphometric and meristic data for
Melanochromis mpoto
from Katale Island, MalaŴi (holotype and 5 paratypes) and from Chitande Island, MalaŴi (9 paratypes). Ranges include the holotype.
Melanochromis mpoto
holotype
mean range
Snout length 34.1 32.9 29.0–36.8
| Standard length, mm |
86.6 |
67.5 |
50.9–91.1 |
| Head length, mm |
30.2 |
23.9 |
18.0–32.0 |
|
% standard length
|
| Head length |
34.9 |
35.4 |
34.4–36.5 |
| Body depth |
32.3 |
29.8 |
26.8–33.4 |
| Snout to dorsal |
35.4 |
36.3 |
35.1–37.9 |
| Snout to pelvic |
39.8 |
39.5 |
37.5–40.8 |
| Dorsal-fin base length |
54.8 |
55.9 |
53.4–57.6 |
| Anterior dorsal to anterior anal |
45.7 |
44.3 |
41.7–47.9 |
| Anterior dorsal to posterior anal |
57.6 |
57.8 |
55.6–61.3 |
| Posterior dorsal to anterior anal |
27.3 |
27.3 |
25.8–29.4 |
| Posterior dorsal to posterior anal |
13.4 |
14.1 |
13.3–15.1 |
| Posterior dorsal to ventral caudal |
18.1 |
17.5 |
16.4–18.5 |
| Posterior anal to dorsal caudal |
20.6 |
20.0 |
18.7–20.9 |
| Anterior dorsal to pelvic-fin origin |
32.0 |
30.1 |
27.5–34.2 |
| Posterior dorsal to pelvic-fin origin |
54.9 |
54.1 |
51.3–57.8 |
| Caudal-peduncle length |
15.2 |
13.9 |
12.1–16.0 |
| Least caudal-peduncle depth |
12.0 |
11.5 |
10.6–12.7 |
| Pectoral-fin length |
22.1 |
22.5 |
21.2–24.5 |
| Pelvic-fin length |
27.6 |
27.3 |
22.1–33.4 |
| % head length |
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.
|
TABLE 4.
(Continued)
|
|
Melanochromis mpoto
|
holotype
|
mean
|
range
|
| Horizontal eye diameter |
25.5 |
27.7 |
24.1–31.2 |
| Vertical eye diameter |
24.4 |
26.9 |
23.9–29.1 |
| Head depth |
72.2 |
68.9 |
63.3–73.2 |
| Preorbital depth |
19.6 |
17.8 |
15.4–20.4 |
| Cheek depth |
16.4 |
17.6 |
15.4–21.7 |
| Lower jaw length |
41.2 |
39.9 |
38.1–42.4 |
| Interorbital width |
19.6 |
17.2 |
14.8–21.8 |
| Premaxillary length |
28.4 |
27.1 |
24.2–29.1 |
|
Meristics
|
holotype
|
mode
|
range
|
| Dorsal-fin spines |
17 |
17 |
17–18 |
| Dorsal-fin rays |
9 |
9 |
9–10 |
| Anal-fin spines |
3 |
3 |
3 |
| Anal-fin rays |
7 |
8 |
7–8 |
| Pectoral-fin rays |
13 |
13 |
12–14 |
| Pelvic-fin rays |
5 |
5 |
5 |
| Lateral-line scales |
32 |
32 |
31–32 |
| Pored scales post lateral line |
1 |
2 |
0–3 |
| Cheek-scale rows |
6 |
6 |
5–7 |
| Gillrakers 1st ceratobranchial |
10 |
10 |
9–11 |
| Gillrakers 1st epibranchial |
3 |
3 |
3–4 |
| Teeth in outer series of left lower jaw |
19 |
22 |
18–23 |
| Tooth rows in upper jaw |
4 |
4 |
3–5 |
| Tooth rows in lower jaw |
4 |
3 |
3–4 |
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.