Orthochromis kimpala, Schedel & Vreven & Manda & Abwe & Manda & Schliewen, 2018

Schedel, Frederic Dieter Benedikt, Vreven, Emmanuel J. W. M. N., Manda, Bauchet Katemo, Abwe, Emmanuel, Manda, Auguste Chocha & Schliewen, Ulrich Kurt, 2018, Description of five new rheophilic Orthochromis species (Teleostei: Cichlidae) from the Upper Congo drainage in Zambia and the Democratic Republic of the Congo, Zootaxa 4461 (3), pp. 301-349 : 318-323

Orthochromis kimpala sp. nov.

Holotype. MRAC 2012-031 -P-2096 (84.58 mm SL), Democratic Republic of the Congo, Kalule Nord River, right tributary of Lualaba River, near to the bridge on road Makulakulu-Lubudi (-9.6935/25.8479).

Paratypes. ZSM 46849 (2, ex MRAC uncat., 62.7–78.8 mm SL), collected with holotype .— ZSM 46850 (1, ex MRAC uncat., 44.0 mm SL), collected with holotype .— MRAC 2015-005 -P-0032-0033 (2, 56.9–62.6 mm SL), Democratic Republic of the Congo, Kalule Nord River , bridge Lubudi-Luena (-9.693472/25.847833). — MRAC 2015-005 -P-0034-0035 (2, 56.3–60.5 mm SL), Democratic Republic of Congo, Kalule Nord River , Kyabule village, bridge Mukulakulu-Kolwezi (-9.66725/25.740056). — MRAC 2015-005 -P-0036-0037 (2, 57.7–61.3 mm SL), Democratic Republic of the Congo, Kalule Nord River , Kyabule village, bridge Mukulakulu-Kolwezi (- 9.66725/25.740056).

Differential diagnosis. Orthochromis kimpala can be readily distinguished from all species currently placed in Orthochromis (sensu de Vos & Seegers, 1998) except O. torrenticola , by presence of eggspot-like maculae on anal fin. Further, it is distinguished from Malagarasi- Orthochromis species, including O. sp. “Igamba”, by having more scale rows on cheek (3–4 vs. 0 or 0–1 in case of O. mazimeroensis and O. rubrolabialis ). Furthermore, O. kimpala differs from O. luichensis , O. malagaraziensis , O. mazimeroensis , O. mosoensis , and O. rubrolabialis by having more scales between upper lateral line and dorsal-fin origin (6–7 vs. 4–5). Additionally, it has fewer dorsalfin spines than O. luichensis , O. malagaraziensis , and O. rubrolabialis (15–16 vs. 17–19). Moreover, it differs from O. rubrolabialis by having more total gill rakers (11–12 vs. 8–9) and by position of pterygiophore supporting last dorsal-fin spine (vertebral count: 14-16 vs. 17-19); from O. mazimeroensis by having more abdominal vertebrae (14–15 vs. 12–13); from O. mosoensis by having more scales (horizontal line) on operculum (3 vs. 0–1). O. kimpala is distinguished from O. kasuluensis , O. rugufuensis and O. uvinzae by having fewer dorsal-fin spines (15–16 vs. 17-20); from O. kasuluensis and O. rugufuensis by having more scales (horizontal line) on operculum (3 vs. 1–2); from O. kasuluensis and O. uvinzae by having fewer scales in upper lateral line (20–22 vs. 23–25) and fewer total vertebrae (28–30 vs. 31–33). Moreover,it differs from O. uvinzae by having fewer horizontal line scales (27–29 vs. 30–32) and by position of pterygiophore supporting last dorsal-fin spine (vertebral count: 14–16 vs. 18– 19). It can be distinguished from O. kalungwishiensis , O. luongoensis , O. polyacanthus , and O. torrenticola by having fewer dorsal-fin spines (15–16 vs. 17–20); further from O. kalungwishiensis , O. luongoensis , and O. torrenticola by fewer horizontal line scales (27–29 vs. 30–32) and fewer total vertebrae (28–30 vs. 31–33); from O. luongoensis and O. torrenticola by fewer caudal vertebrae (13–16 vs. 17–18); from O. torrenticola by having fewer anal-fin spines (3 vs. 4). Moreover, it is distinguished from O. torrenticola and O. polyacanthus by position of pterygiophore supporting last anal-fin spine (vertebral count: 14–15 vs. 16–17). It is distinguished from O. stormsi by having fewer total gill rakers (11–12 vs. 13–15). It differs from S. neodon by having more scale rows on cheek (3–4 vs. 1–2), fewer horizontal line scales (27–29 vs. 30–31), more circumpeduncular scales (16 vs. 12), fewer inner series of teeth (2–3 vs. 4–6). It differs from H. snoeksi by having fewer horizontal line scales (27–29 vs. 30– 31), fewer scales on upper lateral line (20–22 vs. 23), more abdominal vertebrae (14–15 vs. 13) and fewer caudal vertebrae (13–16 vs. 17), more anal-fin rays (8–10 vs. 5–6) and more total gill rakers (11–12 vs. 9); from H. bakongo by having more scales between upper lateral line and dorsal-fin origin (6–7 vs. 3–5); from H. moeruensis by having more upper procurrent caudal-fin rays (6–7 vs. 5) and more total caudal-fin rays (26–27 vs. 28–29); from H. vanheusdeni by having more scale rows on cheek (3–4 vs. 0–2). It is distinguished from herein newly described species O. mporokoso by more scales between upper lateral line and dorsal-fin origin (6–7 vs. 4–5); from O. katumbii by having fewer horizontal line scales (27–29 vs. 30–31), and by more scales between upper lateral line and dorsal-fin origin (6–7 vs. 4–5); from O. gecki by having more series of scales on cheek (3–4 vs. 0–2); from O. indermauri by having more series of scales on cheek (3–4 vs. 1–2) and by fewer dorsal-fin spines (15–16 vs. 17– 18).

Description. Morphometric measurements and meristic characters are based on 10 type specimens. Values and their ranges are presented in Table 4. For general appearance see figure 5. Maximum length of wild caught specimens 84.6 mm SL. Moderately slender species with maximum body depth (24.8–30.5 % SL) at level of first dorsal-fin spine, decreasing rather quickly towards caudal peduncle. Caudal peduncle rather short and deep (ratio of caudal peduncle length to depth: 1.2–1.4). Head length almost one third of standard length. Dorsal-head profile rather strongly curved and without a prominent nuchal gibbosity. Eye diameter larger than interorbital width. Jaws isognathous. Posterior tip of maxilla reaching or almost reaching to anterior margin of orbit. Lips not noticeably enlarged or thickened, but upper lip becoming thicker posteriorly. Two separate lateral lines.

Squamation. Flank above and below lateral lines covered with comparatively large, well developed ctenoid scales. Anterior dorsal and ventral flank covered by cycloid scales. Margin of belly with deeply embedded medium sized scales; central belly region scaleless. Chest covered with minute, deeply embedded cycloid scales, giving impression of a scaleless chest; chest to flank transition with larger cycloid scales, however, still deeply embedded. Snout scaleless. Interorbital scales minute to small, cycloid and deeply embedded. Nape region covered with small, deeply embedded cycloid scales becoming slightly larger towards occipital region. Occipital region with small to medium sized cycloid scales. Cheek covered by medium sized cycloid scales; 3–4 scale rows on cheek. Cycloid scales on operculum of medium size and variable shape (ovoid to circular); opercular blotch only on anterior margins covered by medium sized scales, main area of opercular blotch scaleless. Three scales on a horizontal line starting from edge of postero-dorsal angle of operculum to anterior edge of operculum.

......continued on the next

Upper lateral line scales 20–22 and lower lateral line 8–11. Horizontal line scales 27–29. Caudal fin with 0–2 pored scales. Upper and lower lateral lines separated by two scales; 6–7 scales between upper lateral line and dorsal-fin origin. Anterior part of caudal fin covered with 2–3 vertical rows of small cycloid scales; with median scales slightly larger; scaled area of caudal fin extended posteriorly especially at upper and lower area with minute, interradial scales (approximately up to one half of caudal fin). Sixteen scales around caudal peduncle.

Jaws and dentition. Anterior teeth of outer row of upper and lower jaw bicuspid to subequal bicuspid, large and moderately closely set; towards corner of mouth, teeth smaller and more widely set and unicuspid. Individual bicuspid teeth with minimally expanded brownish crown, cusps uncompressed and moderately narrowly set, neck moderately stout. Outer row of upper jaw with 30–47 teeth and outer row of lower jaw with 28–38 teeth (specimens: 44.4–84.6 mm SL); larger specimens generally with more teeth. Two to three inner upper and lower jaw tooth rows with small tricuspid teeth (rarely bicuspid).

Lower pharyngeal bone ( Fig. 5 ) of single dissected paratype (ZSM 46849, 62.7 mm SL) about 1.2 times wider than long with anterior keel about 0.5 times of length of dentigerous area. Dentigerous area of lower pharyngeal bone about 1.6 times wider than long, with 11+11 (empty tooth-sockets included) teeth along posterior margin and eight teeth along midline. Anterior pharyngeal teeth (towards keel) bevelled to pronounced and slender; those of posterior row larger than anterior ones, bevelled (minor cusp not well developed). Largest teeth medially situated in posterior tooth row. Teeth along midline slightly larger than more lateral ones.

Gill rakers. Total gill raker count 11, with 2–3 epibranchial, one in angle, and 7–8 ceratobranchial gill rakers. Most anterior ceratobranchial gill rakers smallest increasing quickly in size towards cartilaginous plug (angle). Gill raker in angle slightly shorter than longest ceratobranchial gill raker and epibranchial gill rakers further decreasing in size.

Fins. Dorsal fin with 15–16 spines and with 10–11 rays. First dorsal-fin spine always shortest. Dorsal-fin base length between 51.4–56.9 % SL. Posterior end of dorsal-fin rays reaching or slightly extending beyond caudal fin base; posterior tip of anal fin ending slightly before caudal fin base. Caudal fin outline subtruncate and fin composed of 28–29 rays (16 principal caudal-fin rays and 12–13 procurrent caudal-fin rays). Anal fin with 3 spines (3rd spine longest) and 8–10 rays. Anal-fin base length between 17.4–20.6 % SL. Pectoral fin with 14–16 rays. Pectoral-fin length between 20.6–24.8 % SL; longest pectoral ray not reaching level of anus. First upper and lower pectoral-fin rays very short to short. Pelvic fin with 1 st spine thickly covered with skin and five rays. Pelvic-fin base slightly more posterior than pectoral fin base. Longest pelvic-fin ray not reaching anus (ending approximately 3 flank scale widths before).

Vertebrae and caudal fin skeleton. 28–30 total vertebrae (excluding urostyle element), with 14–15 abdominal and 13–16 caudal vertebrae. Pterygiophore supporting last dorsal-fin spine inserted between neural spines of 14th and 15th, 15th and 16th or 17th and 18th vertebra (counted from anterior to posterior). Pterygiophore supporting last anal-fin spine is inserted between rips of 14th (or 15th) and haemal spine of 15th (or 16th) vertebra or between haemal spine of 15th and 16th vertebra. Single predorsal bone (=supraneural bone) present. Hypurals 1 and 2 as well as hypurals 3 and 4 clearly separated (most common state) or fused while any other combination is possible (e.g. hypurals 1 and 2 fused and hypurals 3 and 4 separated or vice versa).

Colouration in life (based on field photographs of adult specimens). Body ground colouration pale brown to beige; dorsum, flank and caudal peduncle light brown; belly whitish; chest whitish to yellow. Dark grey to blackish, interrupted midlateral band from operculum to just behind caudal fin base, ending in dark blotch; midlateral band crossed by 7–9 light grey vertical bars (sometimes hardly visible) extending mainly dorsally; at level of upper lateral line most bars fuse forming dorso-lateral band which extends to posterior origin dorsal fin. Scales on flank and dorsum with orange blotch on anterior surface and greenish metallic highlights, especially scales on or row above or below lower lateral line. Dorsal head surface brownish; anterior snout brownish, preorbital area and cheek yellowish to brownish; mental area and ventral parts of preoperculum and cheek light bluish. Operculum yellowish with brownish sprinkles; black opercular spot present. Greyish vertical preopercular stripe of variable intensity is always present, at least in the form of a faint blackish blotch at mid orbit level. Dark grey to brownish lachrymal stripe between orbit and posterior end upper lip. Greyish to brownish nostril stripe (less intense than lachrymal stripe) fused posteriorly with lachrymal stripe. Faint greyish interorbital stripe. Upper lip brownish to olive, beige to light bluish posteriorly and lower lip beige to light bluish. Dorsal fin membrane greyish with orange margins; soft rayed part of dorsal fin with orange maculae arranged in 2–3 rows. Anal-fin membrane greyish, margin of spinous part dark grey; 2–3 orange maculae on soft rayed part anal fin. First macula situated just posterior last anal-fin spine at outer margin of anal fin. Second macula almost in centre of rayed part anal fin. When present, third macula less prominent (smaller and less colourful). Maculae resembling eggspots but without white concentric ring. Caudal fin yellowish with grey margin and four columns of small orange maculae. Pectoral fin yellowish. Pelvic fin yellowish; skin around pelvic fin spine and adjacent membrane of first two rays blackish.

Juvenile colouration in live. No information about juvenile colouration available.

Colouration in alcohol. Colouration and melanin patterns similar to live specimens, but due the preservation procedure of specimens, i.e., first formalin fixation, transfer to 75 % EtOH etc., specimens tend to lose original colouration (especially melanin patterns more intense than in live specimens). Overall body ground colouration brownish; dorsum and flank brownish. Orange blotches on flank scales no longer visible. Chest and belly beige to light brown. Branchiostegal membrane greyish brown. Dorsal head surface brownish, ethmoidal region greyish brown. Upper lip greyish; lower lip greyish anteriorly becoming beige. Cheek light brown to brownish. Preoperculum greyish. Operculum dark brown to greyish with opercular spot as described above. Head mask dark brownish to grey. Midlateral band, vertical bars and dorso-lateral band brownish. Dorsal fin greyish, lappets with very fine black seam; maculae on soft-rayed part beige. Anal fin greyish; margin dark grey to black, eggspot-like maculae whitish. Caudal fin greyish with dark greyish margin; maculae dark grey. Pectoral fin light grey. Pelvic fin light grey, skin around pelvic fin spine and adjacent membrane of first two rays dark grey.

Distribution and biology. Orthochromis kimpala is known from the Kalule Nord River ( Fig. 1 ), a right tributary of the Lualaba River in the Democratic Republic of the Congo. At the type locality the Kalule Nord River has a rocky bottom with some patches of sand and gravel, and is about 5–8 meters wide and on average about 50 cm deep ( Fig. 8 ). Water temperature varied between 21.1 and 26.8 °C (measured over several years in August and September), pH between 7.95–8.71, electrical conductivity 333.5–359 µS. The species appears to be benthicrheophilic.

Etymology. The species name kimpala refers to the local name for this species: “Kimpala” in the Sanga language. A noun in apposition.

Figures

FIGURE 1. Map of south-eastern DRC and Northern Zambia, with indications of the type localities of the known Orthochromis species of the Upper Congo drainage system and new Orthochromis species. Star = type locality, circle = either paratype locality or sample locality of comparative specimens. Species indicated by colour: O. mporokoso sp. nov. (light blue); O. katumbii sp. nov. (purple); O. kimpala sp. nov. (orange); O. gecki sp. nov. (deep orange); O. indermauri sp. nov. (deep blue); O. kalungwishiensis (dark red); O. luongoensis (green). O polyacanthus (brown) and O. torrenticola (yellow). Major citys are depicted in black. Map is based on shapefiles obtained from DIVA-GIS (http://www.diva-gis.org/Data).

FIGURE 5. Orthochromis kimpala sp. nov. A. probably the holotype, alive B. Holotype, (MRAC 2012-031-P-2096), 84.6 mm SL; Democratic Republic of the Congo, Kalule Nord River stream C. radiograph of holotype D. lower pharyngeal bone (specimen: ZSM 46849, 62.7 mm SL) E. Overview of arrangement and morphology of oral jaw teeth (specimen: MRAC 2015- 005-P-0036-0037, 61.3 mm SL).

FIGURE 8. Type localities of the five newly described species A. Type locality of Orthochromis mporokoso, Kasinsha stream (July 2011, Hans van Heusden) B. Type locality of Orthochromis katumbii, Kiswishi River (2015, VLIR expedition) C. Type locality of Orthochromis gecki, Lubudi River (July 2017, Katanga 2016 Expedition) D. Type locality of Orthochromis kimpala, Kalule North River near bridge on the road Makulakulu-Lubudi (2012, PRODEPAAK expedition) E. Type locality of Orthochromis indermauri, Lufubu River at Chomba village (August 2015, photo F. Schedel).