Labeotropheus rubidorsalis, Phiri and Pauers, 2023

Pauers, Michael J. & Phiri, Titus B., 2023, Six New Species of Labeotropheus (Cichliformes: Cichlidae) from the Malaŵian Shore of Lake Malaŵi, Africa, Ichthyology & Herpetology 111 (2), pp. 263-292 : 287-290

Labeotropheus rubidorsalis, Phiri and Pauers , new species

urn:lsid:zoobank.org:act:594EFD55-FB60-44DF-801F- C2B747E5865D

Figures 3 , 13 , 14 ; Tables 4, 14, 15

Holotype.— SAIAB 211383, adult male, 91.2 mm SL, Malaŵi, Lake Malaŵi, Maleri Island, –13.8840189, 34.6118803, Michael J. Pauers, Titus B. Phiri, and Sanudi Likupe, 16 January 2020.

Paratypes.— FMNH 145014, 1 male, 91.3 mm SL, 1 female, 81.6 mm SL, Malaŵi, Lake Malaŵi, Maleri Island, –13.8840189, 34.6118803, Michael J. Pauers, Titus B. Phiri, and Sanudi Likupe, 16 January 2020; MPM Fi50090, 5 females, 69.3–88.5 mm SL, Malaŵi, Lake Malaŵi, Maleri Island, –13.8840189, 34.6118803, Michael J. Pauers, Titus B. Phiri, and Sanudi Likupe, 16 January 2020; SAIAB 211382, 3 females, 67.5, 74.03, and 81.3 mm SL, Malaŵi, Lake Malaŵi, Maleri Island, –13.9089591, 34.6260792, Michael J. Pauers, Titus B. Phiri, and Sanudi Likupe, 16 January 2020.

Diagnosis.— Labeotropheus rubidorsalis differs from all other described species of Labeotropheus due to the nuptial color pattern of the males. The males have a vivid, almost metallic, blue head, body, and caudal peduncle, and an equally brilliant red dorsal fin. Labeotropheus rubidorsalis also differs from all other Labeotropheus by the shape of the anal fin. All other species of Labeotropheus have an angular to kite-shaped anal fin, but L. rubidorsalis has a distinctly rounded anal fin, especially in the posterior portion.

Labeotropheus rubidorsalis has a generally slenderer body than the most of the robust Labeotropheus , though its range overlaps that of several of these species (31.6–36.1% SL vs. 37.4–40.6% in L. alticodia , 34.3–42.0% in L. artatorostris , 33.8–41.5% in L. aurantinfra , 32.0–38.6% in L. candipygia , 31.9–34.7% in L. chlorosiglos , and 35.2–41.5% in L. obscurus ). Labeotropheus rubidorsalis does have a distinctly slenderer body than some of these species as measured by the distance between the origins of the dorsal and anal fins (45.6–50.3% SL vs. 52.1–53.5% in L. alticodia , 50.2–58.1% in L. artatorostris , 51.3–54.6% in L. chlorosiglos , 52.5–55.5% in L. fuelleborni , and 50.8–56.3% in L. obscurus ) and the insertion of the dorsal and anal fins (13.5–15.7% SL vs. 16.4–18.1% in L. alticodia , 15.4–18.3% in L. artatorostris , 15.5–16.8% in L. chlorosiglos , 16.5–17.4% in L. fuelleborni , and 15.8–17.8% in L. obscurus ). Labeotropheus rubidorsalis has fewer rows of teeth in the upper jaw (3–4) than L. artatorostris (5–8), L. aurantinfra (4–6), L. fuelleborni (4–5), and L. candipygia (4–6). Labeotropheus rubidorsalis also has fewer rows of teeth in the lower jaw (3–5) than L. fuelleborni (6) and L. chlorosiglos (5–7).

Labeotropheus rubidorsalis is typically deeper-bodied than the slender-bodied Labeotropheus as indicated by both body depth (31.6–36.1% SL vs. 26.6–33.2% in L. chirangali , 26.3– 33.4% in L. trewavasae ; and 26.9–30.8% in L. simoneae ) and by the distance between the origin of the dorsal fin and the attachments of the pelvic fins (31.5–35.4% SL vs. 28.6–33.4 in L. chirangali , 27.1–32.7% in L. trewavasae ; and 27.5–32.8% in L. simoneae ). Labeotropheus rubidorsalis also has fewer rows of teeth in the upper jaw than the other slender species (3–4 vs. 3–6 in L. chirangali , 4–7 L. simoneae , and 5–7 L. trewavasae ). It also has fewer rows of teeth in the lower jaw than L. trewavasae (3–5 vs. 5–6).

Description.— Morphometric and meristic data summarized in Table 14. Body compressiform with flattened ovoid shape; body consistently deep throughout its length, especially for a slender Labeotropheus . Body wide, almost cylindrical in transverse cross section. Scales on belly and anterior abdomen cycloid and tightly crowded. Flank scales ctenoid; exposed portion of scale fan-shaped and approximately hexagonal. Anterior lateral line overlapping posterior lateral line by 0–3 scales. Dorsal fin long, 56.0–62.6% SL with 17–19 spines and 7–8 rays. Origin of dorsal fin posterior to or overlapping opercular tab. Dorsal-fin rays 3, 4, 5 long, reaching to hypural and beyond to caudal fin. Anal fin rounded posteriorly in all specimens. Origin of anal fin opposite dorsal-fin spine 14, 15, or 16; insertion of anal fin anterior to insertion of dorsal fin. Anal-fin rays 3, 4, 5 reach past hypural in males; only reach to mid-caudal peduncle in females. Caudal fin subtruncate. Pectoral fin long and rounded, with 13–15 rays. Pelvic fin long, minimally reaching origin of anal fin and longer in the majority of specimens. Pelvic-fin ray slightly produced and filamentous in half of specimens; non-filamentous in other half. Pelvic-fin attachment opposite dorsal-fin spine 4, 5, or 6.

Head long and deep, especially for a slender-bodied Labeotropheus ; head depth 91.6–105.0% HL. Head profile moderately curved with no concavity above eye. Snout long and wide with slightly protruding snout; snout pad 10.3– 14.2% HL. Cheek with 3–4 scale rows. Infraorbital pores 7–9, with 8–25 neuromasts distributed among them. Oral jaws long and wide. Oral teeth tricuspid and closely set on upper and lower jaws; 5–12 tricuspid teeth on lateral portion of left upper jaw. Gill rakers stout, triangular, and widely spaced; 5– 8 ceratobranchial and 2–3 epibranchial gill rakers on first gill arch. All specimens with 1 raker between the cerato- and epibranchial rakers.

Coloration of males.— Head, operculum, flank, caudal peduncle brilliant, solid blue; 11 faint bars spanning flank and caudal peduncle. Opercular tab faint metallic green. Dorsal fin brilliant red, fading somewhat posteriorly; small hyaline spots in rayed dorsal fin. Caudal fin same brilliant blue as rest of body, fading posteriorly, with thin red trailing edge. Spinous portion of anal fin white, becoming blue in rayed portion; 3–5 yellow eggspots present. Pelvic fin bluish white posteriorly with white leading edge, pale red between.

Preserved males uniformly gray with 11 bars faintly visible across flank and caudal peduncle.

Coloration of females.— Females with orange blotch (‘OB’) color pattern across entire body and all fins; ground color is pale orange with black, white, and darker orange spots of irregular shape and varying size. Opercular tab black or black with faint green sheen. Anal fin hyaline in some individuals, some individuals with faint orange blotches overlying hyaline anal-fin membrane. All individuals with 1–7 very small orange eggspots present on anal fin.

Preserved females uniformly white or pale gray with dark gray and/or black spots across flank and caudal peduncle.

Multivariate analyses.— Due to the overlap of morphometric and meristic characteristics between L. rubidorsalis and the other Labeotropheus , we compared the body depth–standard length ratios of L. rubidorsalis and its geographically proximate congeners ( Fig. 3 ). This ratio shows that L. rubidorsalis has a body profile that is distinct from that of both the robust and slender Labeotropheus found nearby ( Table 4). We also performed canonical discriminant function analyses on the meristic and Log 10 -transformed morphometric data of L. rubidorsalis and L. trewavasae . While the discriminant function analysis of the Log 10 -transformed morphometric data was not significant (Wilks’ k ¼ 0.005, F 21,1 ¼ 9.109, P ¼ 0.26), the analysis of the meristic data was robust and significant ( Table 15 ). When the first meristic canonical function is plotted as a histogram, L. rubidorsalis is clearly distinct from L. trewavasae ( Fig. 14 ).

Distribution.— Labeotropheus rubidorsalis is endemic to the Malaŵian shore of Lake Malaŵi. We captured specimens at both Maleri and Nankoma Islands, in Lake Malaŵi National Park, and found a similarly colored slender Labeotropheus at Namalenje Island, but only captured two specimens and did not include these in our analyses; Ribbink et al. (1983a) also reported a similarly colored slender Labeotropheus from Namalenje. We did not collect at the nearby Nakantenga Island, where Ribbink et al. (1983a) reported a differently colored slender Labeotropheus .

Etymology.— The specific epithet is a combination of the Latin adjective rubi, meaning red colored, the Latin noun dorsum, meaning the dorsal surface or back, and the Latin suffix - alis, which means pertaining to. This epithet describes the brilliant red dorsal fin of the males.

Figures

FIG. 3. Body depth–standard length relationships among L. fuelleborni, L. trewavasae, and the three new species of Labeotropheus from the southwestern portion of Lake Malaŵi. The ANOVA accompanying these data is in Table 4.

FIG. 13. Labeotropheus rubidorsalis, new species. (A) Live male holotype (SAIAB 211383), 91.2 mm SL; (B) holotype after preservation; (C) live female paratype (MPM Fi50090), 69.4 mm SL.

FIG. 14. Histogram of meristic canonical function 1 for L. rubidorsalis and L. trewavasae.

Tables

Table 15. Canonical discriminant function (CDF) analyses on meristic data for L. rubidorsalis and L. trewavasae; Wilks’ k ¼ 0.038, F6,16 ¼ 66.894, P 0.001. Standardized functions are reported. Uninformative variables are omitted.

	CDF 1
Eigenvalue	25.085
Canonical correlation	0.981
Pectoro-pelvic scale rows	0.720
Dorsal-fin rays (DFR)	–0.660
Pectoral-fin rays	1.410
Upper jaw teeth rows	1.175
Lower jaw teeth rows	1.482
Teeth on left dentigerous premaxilla	–1.499
Species means
L. rubidorsalis	–4.999
L. trewavasae	4.582