Lamprologus markerti, Tougas & Stiassny, 2014

Tougas, Stephanie & Stiassny, Melanie L. J., 2014, Lamprologus markerti, a new lamprologine cichlid (Teleostei: Cichlidae) endemic to the lower Congo River in the Democratic Republic of Congo, west-central Africa, Zootaxa 3852 (3), pp. 391-400 : 393-398

Lamprologus markerti , new species

Figures 1–6 , Tables 1 & 3 .

Holotype: AMNH 238601 , male, 90.0 mm SL, Democratic Republic of Congo, Bas Congo Province , across from Matadi , Congo River at Lufu River confluence, 5°48' 6.60" S, 13°27' 25.80" E, Coll. R. Schelly et al., 19 July 2005.

Paratypes: AMNH 238602 , 6 specimens, 44.5–78.5 mm SL, same locality as holotype .— MRAC B4-10 -P-1, 60.4 mm SL, same locality as holotype .— MCZ 171125 , 54.0 mm SL, same locality as holotype .— AMNH 238603 , 2 specimens, 66.0– 72.5 mm SL, Democratic Republic of Congo, Bas Congo Province , Nziya site, Inga, 05°32' 10.20" S, 13°33' 23.40" E, Coll. M.J. Stiassny et al., 17 July 2007 .— AMNH 238604 , 69.0 mm SL, Democratic Republic of Congo, Bas Congo Province , Nziya , downstream of Inga , below Bundi stream of Congo River confluence, 5°33' 22.20" S, 13°33' 13.20" E, Coll . R. Schelly et al., 16 July 2005 .— AMNH 233568 , 43.0 mm SL, (paratype of L. tigripictilis ), Democratic Republic of Congo, Bas Congo Province , Nziya village, 5°32' 15.00" S, 13°33' 36.60" E, Coll . R. Schelly et al., 24 September 2002 .— AMNH 238652 , 45.0 mm SL, Democratic Republic of Congo, Bas Congo Province , Main channel of Congo River, upstream of Boma, 5°51' 49.80" S, 13° 4' 24.60" E, Coll . R. Schelly et al., 18 July 2005 .— ZSM 37820, 2 specimens, 58.5–64.5 mm SL, Democratic Republic of Congo, Bas Congo Province , Congo River, weeds upriver of boat landing site, 5°51’ 48” S, 13°4’ 28” E, Coll. D. Neumann, 16 July 2008 .— ZSM 38391, 102.5 mm SL, Democratic Republic of Congo, Bas Congo Province , Congo River, purchased at Boma fish market, 5°51’ 46.90” S, 13°4’ 3.99” E, Coll. D. Neumann, 16 July 2008 .

Additional non-type specimens examined: AMNH 238654 , 14 specimens , 2 C&S.— AMNH 241592 , 16 specimens , 1 C&S.— AMNH 238650 , 23 specimens , 6 C&S.

Differential diagnosis. L. markerti is readily distinguished from L. tigripictilis by the presence of 4–6 broad dark bars on the flanks (versus 7–10 narrow bars), and from L. werneri in the possession of 14 (vs. 15) precaudal vertebrae. It differs from both L. tigripictilis and L. werneri in a reduced number of gill rakers on the first arch (9–11 versus 12–17), a longer head (32.1–34.7% SL versus 29.3–31.9 and 29.1–32.9% SL, respectively), and a longer predorsal length (33.0–35.9% SL versus 29.3–32.7 and 28.5–32.6 % SL respectively). Further, L. markerti lacks an intestinal loop present in both L. tigripictilis and L. werneri , and has a highly reduced infraorbital series often consisting only of the first infraorbital (lachrymal) element.

Description. A Lamprologus attaining a maximum-recorded size of 102.5 mm SL (mature male, ZSM 38391), with general body shape and appearance as in Figures 3 and 6A . Counts and proportional measurements for holotype and 16 paratypes as in Table 1 with comparable ranges for L. tigripictilis , the taxon with which it has previously been confused, in Table 2. Body relatively shallow (BD 20.2–24.8% SL), greatest depth at level of first dorsal fin-spine. Head long (32.1–34.7% SL), snout prominent, with well-developed, fleshy lips. Dorsal head profile rises at angle of 40–50° to mid-orbit, then rises steeply to nape. Large males with a prominent, fat filled nuchal hump ( Fig. 3 ). Dorsal and ventral body profiles slightly convex to relatively deep caudal peduncle.

Dorsal fin XVI–XVIII (mode: XVIII) 7 or 8 (mode: 7). Anal fin IV–VI (mode: VI) 5–7 (mode 6). Spines in both fins gradually increase in length posteriorly. Dorsal and anal fins with tapering filamentous extensions to middle of caudal fin, longer in mature males than females. Caudal fin large, paddle-shaped with 14 branched rays; fin often appearing subacuminate in preserved specimens. Pectoral fin short, not reaching anus. Pelvic fins also short but somewhat produced, reaching just short of anus or to between anal fin and anus. Second branched ray in pelvic fin longest in both sexes.

Jaws isognathus, inner and outer row teeth in both jaws pointed unicuspids. Single series of eight enlarged, recurved, procumbent canines situated anteriorly on premaxilla ( Fig. 4A ), with largest pair displaced dorsolaterally. Behind the procumbent canines a single row of slightly enlarged canines gradually taper in size beginning at midlength of premaxilla. Outer row teeth extend almost entire length of both dentary and premaxilla. Lower pharyngeal jaw wider than long, with straight ventral suture ( Fig. 4F ). Usually 24–28 teeth in posterior row, symphysial teeth moderately robust ( Fig. 4E ), become slender laterally. Gill rakers markedly elongate, nondenticulate and slender ( Fig. 4D ). Nine to eleven rakers along outer row of first gill arch; one hypobranchial, 4–6 ceratobranchial rakers, often one raker in angle of arch, and 3 or 4 epibranchial rakers.

Flank scales large, uniformly sized, and ctenoid. Chest and cheek scaleless. Scales on nape and above upper lateral line, to level of 7–9 th dorsal-fin spine, markedly smaller than those on flanks Opercle and subopercle with few, scattered, deeply embedded cycloid scales. Proximal half of caudal fin covered with small ovoid, ctenoid scales. Pored lateral line scales 34–36. Upper and lower lateral lines usually overlap by 2 or 3 scales. Total number of vertebrae: 32 or 33, comprised of 14 precaudal and 18 or 19 abdominal centra.

Supraoccipital crest relatively low, with no frontal ridge extending to neurocranial lateral-line foramen ( Fig. 4B ). Infraorbital series consisting of broad, plate-like first infraorbital (lachrymal) bearing 5 inflated, sensory-canal pores. Small second infraorbital element polymorphically present and, when present, often lacks tubular sensory canal ( Fig. 4C ). In some individuals a second infraorbital element is entirely lacking ( Fig. 6A ).

Digestive tract short; esophagus leads to small bulbous stomach, from which intestine exits left side at transition zone between esophagus and stomach. Intestine exhibits single, rostro-caudad loop before descending to anus ( Fig. 5A ). Total length of tract (unraveled but not stretched) c. 40–50% SL ( Table 3 ).

Coloration in life ( Fig. 3A ): in mature males, base body coloration mauve gray becoming pale silver ventrally. Turquoise reflective streak under eye, on posterior of cheek, and extending over opercle. Flank scales ringed with dark pigment strongly contrasting with silvery central field. Four or 5 dark vertical bars of uniform thickness, originating at base of dorsal fin and extending over flanks but not reaching to ventrum. Dorsal, anal and caudal fins proximally covered with alternating pale and dark spotting. Pectoral fin clear, pelvic fin pale silver along distal margin. Scaleless, dark, opercular spot obscured by turquoise iridescence. In preservation ( Figs. 3B & 6A ), base body coloration creamy brown, slightly darker dorsally becoming pale cream ventrally. Four or 5 dark vertical bars on flanks, and flank scales ringed with brown pigment contrasting with pale cream central field. Dorsal and anal fins brown with alternating pale and dark maculae variously evident, but always present. Caudal fin membranes with conspicuous rows of maculae, strongest proximally. All fin spotting more prominent in mature males than in females and juveniles.

Distribution ( Fig. 1 ). L. markerti occupies a roughly 100-km stretch of the LCR from the region of Nziya Village located below the large Inga Rapids to the start of the short Congo estuary just below Boma. The species appears to be a habitat generalist found over a range of substrates from marginal riffle and rocks near rapids, to stiller water habitats over sand and mud.

Etymology. Named for Jeffrey Markert whose initial analyses of cichlid population structure in the region of the large Inga Rapids stimulated this morphological study.

Figures

FIGURE 1. Distributional range of Lamprologus markerti, and sampled L. tigripictilis localities along the lower Congo River, west-central Africa.

FIGURE 2. (A) Principal Components Analysis of body shape, with inset plot of percentage variance explained by each Principal Component, (B) Deformation implied by PC1 scores using Procrustes superposition of 16 homologous landmarks.

FIGURE 3. AMNH 238601, holotype of Lamprologus markerti. (A) in life, (B) in preservation.

FIGURE 4. Lamprologus markerti, AMNH 238650. (A) premaxilla, B) neurocranium, (C) infraorbital series, (D) first gill arch, (E) lower pharyngeal jaw in dorsal view, (F) lower pharyngeal jaw in ventral view. Elements not drawn to scale.

FIGURE 5. Digestive tracts (slightly unraveled for clearer depiction of morphology), after removal of liver, pancreas, gallbladder, spleen and adherent tissues. (A) Lamprologus markerti, (B) L. tigripictilis, (C) L. werneri. Dashed ovals enclose second intestinal loop.

FIGURE 6. (A) AMNH 238602, Lamprologus markerti, new species, paratype (female), (B) AMNH 233609, L. tigripictilis, holotype (male), (C) AMNH 238603, L. werneri, male. Infraorbital series inset on left (not drawn to scale).