Metriaclima gallireyae , new species

Figures 5 , 6 , 7 ; Tables 2

Pseudotropheus lanisticola (in part), Konings 1989

Pseudotropheus livingstonii (in part), Konings 1995

Metriaclima livingstonii (in part), Konings 2001

Metriaclima sp. ‘lanisticola north’ Konings 2007

Key Value
id 1DED3CDA8B372C08FF20FF74B9D93E15
ID-GBIF-Occurrence 3387244304
accessionNumber PSU 13370
collectingDate 2008-01-15
collectionCode PSU, R
collectorName A. F. Konings & J. R. Stauffer Jr.
country Malawi
county Africa
latitude -10.500153
location Gallireya Reef
longitude 34.23336
municipality Lake
specimenCode PSU 13370
specimenCount 1
typeStatus holotype
typeStatusHolotype . specimenCodePSU 13370 , specimenCountadult male , quantity54.4 mm SL, ( geoCoordinate10.500153 S , geoCoordinate34.233362 E ), locationGallireya Reef , locationLake Malaŵi , collectingCountryMalaŵi , collectingCountyAfrica , date 15 Jan. 2008 , collectorNameA. F. Konings & collectorNameJ. R. Stauffer Jr.

Key Value
id 1DED3CDA8B372C08FF70FECCB8F73E72
ID-GBIF-Occurrence 3387244303
accessionNumber PSU 13371
collectingDate 2008-01-15
collectionCode PSU
collectorName A. F. Konings & Stauffer Jr.
country Malawi
county Africa
latitude -10.500153
location Gallireya Reef
longitude 34.23336
municipality Lake
specimenCode PSU 13371
specimenCount 1
typeStatus paratype
typeStatusParatypes . specimenCodePSU 13371 , 20, ( quantity36.4–54.4 mm SL), data as for holotype

Diagnosis. The moderately sloped vomer (49.6º in typeStatusholotype ) with a swollen rostral tip ( Fig. 6 ) and bicuspid teeth in the anterior portion of the outer row of both upper and lower jaws place this species in Metriaclima . The presence of a black submarginal band in the dorsal and anal fin, and 4–5 bars below the dorsal distinguishes M. gallireyae from most other species in Metriaclima , except for M. ngarae . It differs from M. ngarae by a smaller interorbital width (30.7–37.4% vs. 23.6–29.7% HL) and by a smaller ratio of the snout length in the distance between snout tip and pelvic fin origin (20.6–27.8% vs. 28.7–32.8% SNP2). On average the ratio of premaxillary pedicel length in snout length is greater in M. gallireyae at 44.6% vs. 35.1 %SNL in M. ngarae (ranges 33.1–62.7 vs. 20.3–45.2 %SNL). Mature males of M. gallireyae have a dark brown to blue coloration on flank ( Fig. 7 ) on which no bar pattern is visible. Male M. ngarae resemble females and display 4–5 dark bars on a light-colored flank. Female M. gallireyae have a similar color pattern to those of M. ngarae but the bars on the flank are more prominent and extend to the abdomen.

FIGURE 5. Metriaclima gallireyae . Holotype, PSU 13370, adult male, 54.4 mm SL, Gallireya Reef, Lake Malaŵi.

Description. Morphometric and meristic data in Table 2 . Small mbuna with ovoid body (mean BD 38.6% SL) with greatest depth between the 3 rd and 4 th dorsal spine. Dorsal body profile with gradual curve downward posteriorly (more pronounced than in M. ngarae ) with highest point between the 4 th and 5 th spine, less deep towards posterior end of dorsal fin and beginning of caudal peduncle; ventral body profile flat between pelvic fins and origin of anal fin with slight upward angle to caudal fin. Dorsal head profile round with continuous curve between interorbital and dorsal-fin origin; short snout with isognathous to slightly retrognathous jaws; teeth in upper and lower jaws in 3–4 rows (mode 3); teeth in outer row bicuspid, inner rows unicuspid or tricuspid.

Dorsal fin with XVI or XVIII (mode XVII) spines and 7–9 (mode 8) rays. Anal fin with III spines and 7–8 rays. First 5–6 dorsal-fin spines gradually longer posteriorly with sixth spine about twice as long as first spine; posterior 13 spines slightly longer posteriorly with last spine longest; soft dorsal fin with subacuminate tip, 2nd or 3rd ray longest, extending to approximately 1/3–1/2 length of caudal fin. Anal-fin spines progressively longer posteriorly; 3 rd or 4 th ray longest, extending to halfway caudal fin, equal to or slightly further posterior than tip of dorsal fin. Caudal fin subtruncate to emarginate. Pelvic fin reaching to first anal-fin spine. Pectoral fin rounded, paddle-shaped, short, reaching vertical through base of 10th or 11th dorsal-fin spine. Flank scales ctenoid with small scales on breast and belly; 29–32 (mode 30) lateral-line scales, cheek with 4–5 rows of small scales. Small scales over proximal ¼ of caudal fin.

Head of male brown with dark brown interorbital bar; cheek and preopercle with blue highlights; opercle with blue and green highlights and black spot; throat brown ( Fig. 7 ). Flank dark brown to blue (in territorial males), center of scales brown with blue outline; 4–5 brown bars, obscured in fully mature males; breast and belly black. Dorsal fin brown with black submarginal bar; orange and brown lappets, with orange pigmentation in membranes of rayed portion. Caudal fin with black dorsal and ventral margin; brown rays; blue membranes. Anal fin with proximal ¼ gray, distal ¾ black; one yellow ocellus. Pelvic fin black with white leading edge. Pectoral fin with clear membranes and gray rays.

FIGURE 6. CT scan of the cranium of Metriaclima gallireyae . Holotype, PSU 13370, adult male, 54.4 mm SL, Gallireya Reef, Lake Malaŵi; angle of ethmovomerine block is 49.6° with parasphenoid.

Distribution. Metriaclima gallireyae is found on Gallireya Reef ( geoCoordinate10.500153 S , geoCoordinate34.233362 E ), Youngs Bay and in Chitimba Bay ( geoCoordinate10.581122 S , 34.23692 Lake collectingCountryMalaŵi , collectingCountryMalaŵi ( Fig. 1 ).

Field observations. The population density of Metriaclima gallireyae is much higher than that of M. ngarae and is often seen in large groups of up to 20 individuals in the vicinity of empty shells of L. nyassanus . Both sites where this small species was observed contained either many football-sized (lava?) rocks (Gallireya Reef) or large slabs of sandstone (Chitimba Bay) that may provide additional shelter to individuals that were not able to secure an empty shell for protection. The depth range at Gallireya Reef is about quantity8–12 m while the reef (almost solely consisting of sandstone slabs) in Chitimba Bay is at a depth of about quantity 20– specimenCount25 m . Pure sandy habitats in the area of these two reefs were not visited other than near shore (shallower than quantity5 m ) where M. gallireyae was absent.

No stomach analyses were performed but individuals were observed picking from the rocks and slabs, particularly from patches that showed less sediment cover. Repeated application of the fully opened mouth to a sediment-free spot on a rock suggests that it combs the algal matrix for loose strands of (blue-green) algae. Females and immatures were often seen in small foraging groups mainly feeding from plankton in the water column close (< quantity20cm ) to the sandy bottom.

TABLE 2. Morphological and meristic data for Metriaclima gallireyae from Gallireya Reef, Lake Malaŵi, PSU 13370, 13371, n=20. Ranges include holotype.

Variable Holotype Mean Std Dev Range
Standard length (mm) 54.4 45.8 5.0 36.4–54.4
Head length (mm) 17.7 15.1 1.4 12.4–17.7
Percent head length (%)
Snout length 28.3 31.0 2.3 26.2–35.0
Postorbital head length 41.9 42.7 1.8 39.0–46.0
Horizontal eye diameter 32.3 31.1 1.6 28.5–34.2
Vertical eye diameter 30.8 29.0 1.8 25.1–32.4
Preorbital depth 17.9 16.3 1.5 14.1–18.9
Cheek depth 31.1 26.3 3.6 21.1–33.5
Lower jaw length 26.9 26.0 3.0 21.6–33.5
Head depth 104.8 100.1 5.4 91.3–109.7
Inter-orbital width 26.2 27.3 1.5 23.6–29.7
Premaxillary pedicel length 15.7 13.7 1.7 10.9–16.4
Percent standard length (%)
Head length 32.7 33.0 0.8 31.5–34.4
Body depth 43.3 38.6 1.8 34.9–43.3
Snout to dorsal fin origin 39.5 35.7 1.3 32.6–39.5
Snout to pelvic fin origin 38.9 40.6 1.5 37.4–42.5
Dorsal fin base length 60.2 57.2 2.2 52.4–60.2
Anterior dorsal to anterior anal 55.3 51.8 1.7 48.6–55.3
Anterior dorsal to posterior anal 65.3 62.5 1.8 58.0–65.3
Posterior dorsal to anterior anal 34.9 33.0 1.4 30.2–35.0
Posterior dorsal to posterior anal 19.9 18.6 1.0 17.0–19.9
Posterior dorsal to ventral caudal 20.9 19.3 0.9 17.5–20.9
Posterior anal to dorsal caudal 23.2 22.0 0.9 21.0–23.8
Anterior dorsal to pelvic-fin origin 42.7 38.5 1.8 35.0–42.7
Posterior dorsal to pelvic-fin origin 61.1 57.5 1.7 54.7–61.1
Caudal peduncle length 13.6 13.3 1.0 11.5–14.8
Least caudal peduncle depth 15.8 15.6 0.7 14.4–16.3
Meristics Mode Frequency (%) Range
Dorsal-fin spines 17 17 80.0 16–18
Dorsal-fin rays 8 8 80.0 7–9
Anal-fin spines 3 3 100.0 3–3
Anal-fin rays 7 8 75.0 7–8
Pectoral-fin rays 14 14 45.0 12–15
Pelvic-fin rays 6 6 90.0 6–7
Lateral line scales 30 30 40.0 29–32
Pored scales caudal 2 1 40.0 0–3
Cheek scale rows 4 4 85.0 4–5
Gill rakers 1st ceratobranchial 10 10 70.0 9–11
Gill rakers 1st epibranchial 5 4 85.0 3–5
Teeth outer left lower jaw 12 10 25.0 6–17
Tooth rows upper jaw 4 3 70.0 3–4
Tooth rows lower jaw 4 3 90.0. 3–4

Mature males protect an empty shell as their territory but mouth-brooding females at Gallireya Reef were frequently encountered among the rocks of the habitat. Mouth-brooding females in Chitimba Bay were mostly seen near their shell.

Etymology. The specific epithet gallireyae is a genitive of Gallireya Reef, the local name for a reef in Youngs Bay, Lake collectingCountryMalaŵi .

Remarks . There was complete separation of the minimum polygon clusters when the sheared second principal components (SPCA2) of the morphometric data were plotted against the first principal components (PC1) of the meristic data for M. ngarae and M. gallireyae ( Fig. 8 ). The first principal component (size variable) of the morphometric data explained 87.8% of the observed variance and SPCA2 explained 5.4%. Variables that had the highest loadings on SPCA2 were the premaxillary pedicel length (0.89), snout length (-0.24), and cheek depth (- 0.21). The first principal component of the meristic data explained 24.7% of the variance. Variables with the highest loadings on the first principal components of the meristic data were pored lateral-line scales posterior to the hypural plate (0.50), number of tooth rows on the upper jaw (0.44), and tooth rows on the lower jaw (0.28).