Lufubuchromis relictus, Schedel & Kupriyanov & Katongo & Schliewen, 2020

Schedel, Frederic D. B., Kupriyanov, Viviane M. S., Katongo, Cyprian & Schliewen, Ulrich K., 2020, Palaeoplex gen. nov. and Lufubuchromis gen. non, two new monotypic cichlid genera (Teleostei: Cichlidae) from northern Zambia, Zootaxa 4718 (2), pp. 191-229 : 210-219

Lufubuchromis relictus , new species

Haplochromine sp. nov.; Koblmüller et al. 2008

Pseudocrenilabru s sp. ‘Lufubu A’; Koblmüller et al. 2012, Egger et al. 2014, Indermaur 2014

New Lufubu Cichlid; Schedel et al. 2019

Orthochromis sp. “New Lufubu” Meier et al. 2019

Holotype. ZSM 47494, ex ZSM 44312 (5 in lot, now 4), 77.8 mm SL, Zambia, Drainage Congo; Mululwe rapids at Mululwe village , below Mwanyonga falls , trib. to Lufubu River / Lake Tanganyika, 37 km SW of Mpulungu, Northern Province (-9.072543 / 30.932815).

Paratypes. ZSM 44526, 2 , 44.5–93.2 mm SL; Zambia, Drainage Congo; Upper Lufubu River, at bridge on road to Kaponga , 4 km W of Chinakila village, Northern Province (-9.255956 / 30.877441) .— ZSM 44312, 4 , 49.9–56.7 mm SL; collected with holotype .— ZSM 44535, 4 , 40.6–56.9 mm SL; Zambia, Drainage Congo; Luwle creek at bridge on road Mpulungu-Senga Hill, 25 km away from Chinakila village, affluent of Lufubu River , Northern Province (-9.202418 / 30.948029) .— ZSM 41442, 6 , 33.7–70.8 mm SL; Zambia, Drainage Congo; Mululwe stream at bridge on road Lualika-Summe, affluent to Lufubu River , Northern Province (-9.061658 / 31.033958) .– SAIAB 208050 , 3 , ex ZSM 44535 (7 now 4), 44.1–58.7 mm SL; Zambia, Drainage Congo; Luwle creek at bridge on road Mpulungu-Senga Hill, 25 km away from Chinakila village, affluent of Lufubu River , Northern Province (- 9.202418 / 30.948029) .— MRAC 2019.009 .P.0004-0006, 3, ex ZSM 41442, 39.2 –63.0 mm SL; Zambia, Drainage Congo; Mululwe stream at bridge on road Lualika-Summe, affluent to Lufubu River , Northern Province (- 9.061658 / 31.033958) .

Non type: one single juvenile ethanol voucher, field ID DRC-2012/3241, associated to lot ZSM 44312 (not measured or compared for this work).

Diagnosis. Species diagnosis as for genus.

Description. Morphometric measurements and meristic characters are based on 23 type specimens. Values and their ranges are presented in Table 4 . For general appearance see Fig. 6 (male) and Fig. 7 (female). Maximum SL of wild caught male specimen 93.2 mm; largest female is 70.8 mm SL. A comparatively deep bodied (BD: 29.9–34.7% SL) species with maximum body depth slightly before pelvic fin origin, decreasing gently towards caudal peduncle. Ratio caudal peduncle length to depth: 1.3–1.6. HL about one third of SL. Head profile moderately curved, without prominent nuchal gibbosity. Jaws isognathous to slightly retroganthous. Posterior tip of maxilla reaching slightly behind anterior orbit margin. Lips not noticeably enlarged or thickened. Two separate lateral lines.

Squamation. Flank covered with comparatively large ctenoid or, especially in larger individuals, cycloid scales (Supplementary Fig. 3 ). Anterior dorsal flank covered by cycloid scales, ventral flank scales ctenoid to cycloid. Belly with medium sized cycloid to weakly ctenoid scales, approximately half the size of flank scales. Cycloid chest scales smaller than those of belly; chest to flank transition with slightly larger cycloid scales. Snout scaleless. Medium sized interorbital scales cycloid; anteriormost ones partly embedded. Nape and occipital region with slightly smaller cycloid scales (in comparison to flank scales). Cheek covered with small to medium sized cycloid scales; 3–5 scale rows on cheek. Operculum covered with cycloid scales of variable size, from small to about the size of flank scales. Opercular blotch squamated to variable extent; posteriormost margin always scaleless. Three to four scales on horizontal line from anterior edge operculum to posterodorsal margin operculum.

Upper lateral line with 18–22 scales, lower lateral line 9–12 scales and horizontal line with 26–30 scales. Upper and lower lateral lines separated by two scales. Five to eight scales between dorsal-fin origin and upper lateral line; two scales (rarely 3) between origin of last dorsal-fin spine and upper lateral line. Anterior part of caudal fin covered with 3–4 ill-defined vertical columns of small cycloid scales including 0–2 pored scales; scaled area extended posteriorly, with minute, interradial scales covering approximately 25 to 40% of caudal fin. 16 scales around caudal peduncle.

Jaws and dentition. Anterior teeth of outer row of lower and upper jaw subequally bicuspid to equilaterally bicuspid, closely set; teeth slightly smaller and more widely set towards corner of mouth, and becoming unicuspid. Individual bicuspid teeth are recurved and with slightly expanded brownish crown; cusps minimally compressed and moderately wide cusp gap, with tips blunt to pointed; neck moderately stout. Outer row of upper jaw with 25–53 teeth and outer row of lower jaw with 14–48 teeth in (counts for specimens between 16.6 and 93.2 mm SL; larger specimens have more teeth). One to three inner upper and lower jaw tooth rows with small tricuspid teeth.

Lower pharyngeal bone of four paratypes (MRAC 2019.009.P.0004-0006, 63.0 mm SL; ZSM 44312, 56.7 mm SL; ZSM 44535 54.7–56.9 mm SL [keel damaged]) slightly wider than long with width of lower pharyngeal-jaw bone 90–117% of pharyngeal-jaw length ( Fig. 8 ). Dentigerous area of lower pharyngeal-jaw bone about 0.6 to 0.7 times the length of lower pharyngeal bone, with 19–22 teeth along posterior margin of dentigerous area and 6–10 teeth along the sagittal series. Lateral anterior pharyngeal teeth towards keel bevelled to hooked and moderately slender, those of posterior row larger than anterior ones and bevelled with the minor cusp not well developed. Largest teeth located central in posterior tooth row. Teeth along sagittal series slightly larger than more lateral ones.

Gill rakers. Total gill raker count 10–12 with 2–3 epibranchials, one at angle, and 7–8 ceratobranchial rakers. Anteriormost ceratobranchial gill rakers smallest. Gill rakers comparatively stout and unifid, sometimes of anvil or bifid shape towards cartilaginous plug, increasing in size towards cartilaginous plug at angle. Gill raker on cartilaginous plug slightly shorter or as long as longest ceratobranchial gill raker; unifid epibranchial gill rakers further decreasing in length towards cartilaginous plug and slenderer than ceratobranchial gill rakers.

Fins. Dorsal fin with 14–16 spines and with 9–11 rays. First dorsal-fin spine shortest. Dorsal-fin base length between 39.5–55.3 % SL. Posterior end of dorsal fin reaching caudal-fin base or ending slightly behind, especially in males; posterior tip of anal fin reaching caudal-fin base or ending slightly before. Caudal fin outline subtruncate and sometimes or almost slightly emarginate and composed of 26–28 rays (16 principal caudal-fin rays and 10–12 procurrent caudal-fin rays). Anal fin with 3 spines (3 rd spine longest) and 7–8 (rarely 9) rays. Anal-fin base length 14.5–17.9 % SL. Pectoral fin with 13–14 rays. Pectoral-fin length 15.7–26.6 % SL; longest pectoral ray (4 th or 5 th ray counted from dorsal margin) ending slightly before or at level of anus. Pelvic fin with one spine and 5 rays. Pelvicfin base slightly posterior pectoral-fin base, at a distance of approx. twice the flank scale width. Longest pelvic-fin ray reaching level of anus; adult males with slightly elongated 1 st pelvic fin ray.

Axial skeleton. Vertebrae column with 27–29 total vertebrae (excluding the urostyle), with 14–15 abdominal and 13–15 caudal vertebrae. The pterygiophore supporting the last dorsal-fin spine is inserted between the spines of the 13 th and 14 th vertebra, or of the 14 th and 15 th vertebra. The pterygiophore supporting the last anal-fin spine is inserted between ribs or haemal spines of the 14 th, 15 th or 16 th vertebrae. One predorsal bone (=supraneural bone) present. Hypuralia 1 + 2 are either fused without a suture or, rarely, with clearly visible suture; hypuralia 3 + 4 always fused into single sutureless unit.

Coloration in life. Sexual colour dimorphism present. Males with characteristic coloration pattern of deep crimson red coloured areas on the anterior ventral flank parts, chest and belly and on the lower head; remaining parts of flank and caudal peduncle bluish ( Fig 6 .).

Body ground coloration greyish olive to pale brown; dorsum olive to pale brownish, flank and caudal peduncle bluish. Individual flank and caudal peduncle scales on the anterior part of the caudal scale area reddish to brownish/olive; posterior scale area metallic blue.

Anterior ventral flank, belly, and chest deep red; ventral flank whitish. No visible midlateral band present, but 5–8 greyish vertical bars, mostly faint; vertical bars extending from dorsal fin origin to roughly the level of pectoral fin, sometimes irregular in shape, i.e. interrupted or almost blotch-like. Caudal-fin spot present. Iris brownish with some light brown to orange patches. Dorsal head surface and ethmoidal area olive to pale brownish; preorbital area, anterior snout, cheek and preoperculum below level of eye deep crimson red. Operculum olive to pale brownish ventral part deep crimson red; blackish opercular spot with golden to greenish metallic gleam. Faint greyish lachrymal stripe present. Upper lip metallic blue, especially posteriorly, and lower lip whitish to intensive metallic blue, more than upper lip. Branchiostegal membrane white to light grey.

Dorsal fin membrane olive to brownish; dorsal fin lappets orange, same colour as Pseudocrenilabrus blotch in anal fin; dorsal fin lappets delineated by fine whitish submarginal band in spinous part dorsal fin, sometimes extending into soft-rayed part of dorsal; last dorsal fin rays without orange lappets. Soft-rayed part dorsal-fin membrane with irregularly set white to bluish maculae; sometimes few maculae present on spinous part as well. Anal-fin membrane olive to yellowish with irregularly set white to bluish maculae, more prominent than those on dorsal fin; prominent orange Pseudocrenilabrus blotch on posterior margin of soft-rayed anal fin, distal margin Pseudocrenilabrus blotch outlined in black. Caudal-fin membrane olive to yellowish, becoming less intensively coloured towards posterior margin, with irregularly set vertical columns of white to bluish maculae, more prominent than those on dorsal fin; distal margin caudal fin reddish. Pectoral fin transparent or slightly yellowish. Soft-rayed part pelvic fin light yellowish to greyish, membrane of pelvic fin spine grey to bluish.

Females ( Fig. 7 ) not as brightly coloured as males and without prominent red areas on flank, chest, belly, and head. Body ground coloration greyish olive to pale brown. Flank and caudal peduncle without bluish metallic gleam, or, if present, less intensive than in males. Belly and chest region beige to whitish. No visible midlateral band present; 6 to 8 greyish to brownish vertical bars, in most cases clearly visible; vertical bars extending from dorsal fin origin to roughly midlevel of pectoral fin, sometimes of irregular shape, e.g. interrupted, blurred or almost blotch like. Caudal fin spot present. Iris brownish with some light brown to orange patches. Blackish opercular spot with golden to greenish metallic gleam, less intensive than in males. Faint greyish lachrymal stripe present. Upper lip and lower lip whitish to metallic blue, less intensive than in males. Branchiostegal membrane white to light greyish. Dorsal fin, anal fin and caudal-fin membrane similar to males, however, without prominent maculae. Anal fin with orange Pseudocrenilabrus blotch as in males. Pectoral fin and pelvic fin transparent or light yellowish to greyish.

Juvenile coloration in life. (based on tank-raised juveniles of approximately 14.1 mm SL to 21.5 mm SL; Appendix: Supplementary Fig. 4 ).

Body ground coloration whitish to beige. Greyish melanin pattern on flank consisting of irregular blotches and vertical bars (and not regularly shaped vertical bars as in sympatric Pseudocrenilabrus sp. “Lufubu B?” juveniles); up to six blackish stripe-like blotches along dorsal fin base present, forming an interrupted dorsal medial band. Faint grey lachrymal stripe. Iris greyish. Dorsal fin hyaline with few white to bluish spots, all other fins hyaline, no Pseudocrenilabrus blotch on anal fin. Tip of anal-fin membrane light orange in juveniles over ~ 20 mm SL.

Coloration in alcohol. Pigmentation and melanin patterns similar to live specimens, but due to preservation original coloration lost, rendering melanin pattern more intense than in live specimens. Overall body coloration brownish. Chest and belly brownish, particularly in males, to beige. Branchiostegal membrane dusky, especially in males, to light greyish. Ethmoidal area and lips greyish brown. Cheek light brownish; cheek stripe dark brown. Operculum greyish to brownish; opercular spot dark brown. Vertical bars and caudal fin base dark brown; the anterior three to four vertical bars might be connected at the level of the horizontal line. Dorsal fin greyish, dorsal fin lappets transparent to whitish. Anal fin light greyish to grey; Pseudocrenilabrus blotch in males whitish, not visible in females (vs. visible in life). Caudal fin grey brownish. Pectoral fin beige to light grey. Pelvic fin dusky in males and beige to greyish in females.

Distribution and biology. Lufubuchromis relictus is only known from the upper reaches of the Lufubu River and its tributaries, including small streams and creeks, on the northeastern Zambian High Plateaux. The ichthyofauna of the lower Lufubu is clearly different from the one in the upper Lufubu, which appears to be the result of isolation by a series of cascades and waterfalls ( Koblmüller et al. 2012, Schedel et al. 2018). At the type locality, the Mululwe River is about 15 m wide with an estimated average depth of 50 cm; it is rocky with patches of sand and gravel and with few patches of submerged vegetation (e.g. Nymphaea sp.).

No stomach contents were examined but Indermaur (2014) suggested that L. relictus feeds on insect larvae and detritus. Lufubuchromis relictus is a maternal mouthbrooder. In captivity the clutch-size varied between 20 and 30 eggs with an incubation time of 18 to 20 days ( Indermaur 2014). In the wild (Luwle Creek) mouth-brooding females were observed to form groups (pers. obs. F. Schedel).

Etymology. The species name relictus [L.] refers to the restricted distribution of this species in the isolated upper region of an ancient plateau. The basal phylogenetic position of Lufubuchromis (together with Orthochromis kalungwishiensis ) as the ancient mitochondrial sister group of all other members of the Pseudocrenilabrus lineage ( Koblmüller et al. 2008, Schedel et al. 2019) suggests that it represents a relict ancient evolutionary lineage, that once may have had a wider distribution. The specific epithet is an adjective.

Remarks: Comparisons of the two new genera with all other haplotilapiine genera. Based on molecular phylogenetic data Palaeoplex and Lufubuchromis are placed within the informally recognized Pseudocrenilabrus group (see above, Table 1 ). Both new taxa can be distinguished from members of the haplotilapiine tribes Coelotilapiini , Coptodonini , Gobiocichlini , Heterotilapiini , Oreochromini , Pelmatolapiini , Steatocranini and Tilapiini by possessing at least a few weakly ctenoid flank scales (vs. cycloid scales; for details see Dunz et al. 2013). Furthermore, both new genera can be distinguished from the Lake Tanganyika tribes of the haplotilapiine East African cichlid radiation as follows: from Boulengerochromini by having ctenoid scales vs. cycloid scales ( Poll 1986); from Bathybatini (including Trematocara Boulenger 1899b ), Cyphotilapiini (including Trematochromis benthicola ( Matthes 1962)) and Limnochromini by having bicuspid teeth in the outer row of the oral jaws (teeth towards corner of mouth might be unicuspid, though) vs. conical (unicuspid) teeth (in juvenile Cyphotilapia Regan 1920 bicuspid teeth become unicuspid when adult; in addition members of the genus Cyphotilapia develop a distinct hump on the forehead which is not present in Palaeoplex or Lufubuchromis ( Poll 1986, Takahashi 2003b)); from Cyprichromini and Benthochromini by having a rounded to subtruncate caudal fin outline vs. a truncated one ( Takahashi 2003b); from Ectodini by having fewer total vertebrae 27–30 ( Palaeoplex ) / 27–29 ( Lufubuchromis ) vs. 31–38 and fewer horizontal line scales 28–31 ( Palaeoplex ) / 26–30 ( Lufubuchromis ) vs. 32–64 ( Poll 1986, Altner et al. 2017); from Eretmodini by having scales on operculum and cheek vs. a scaleless condition (Lippitsch 1998); from Lamprologini by having three anal fin spines vs. four or more and by having bicuspid teeth in the outer row of the oral jaw vs. conical (unicuspid) teeth ( Poll 1986, Takahashi 2003b); and from Perissodini by having an inner series of teeth in the oral jaw vs. absence of inner teeth series ( Takahashi 2003b).

From the members of Orthochromis s.s. (“Malagarasi- Orthochromis ” sensu Weiss et al. 2015) the new species can be distinguished by fewer dorsal-fin spines 14–15 ( Palaeoplex ) / 15–16 ( Lufubuchromis ) vs. 16–22, and by having more scales on cheek 2–4 ( Palaeoplex ) / 3–5 ( Lufubuchromis ) vs. 0–1 ( Schedel et al. 2018).

Further, Palaeoplex and Lufubuchromis can be distinguished from Ctenochromis pectoralis Pfeffer 1893 , the earliest splitting lineage of Haplochromini (e.g. Verheyen et al. 2003, Koblmüller et al 2008, Schedel et al. 2019), by having fused hypuralia 1+2 (in Lufubuchromis hypuralia 1+2 are either fused or fused with distinctly visible suture) and 3+4 vs. separate hypuralia ( Greenwood 1979); both new taxa can be distinguished from C. pectoralis and other haplochromine cichlids originally placed by Greenwood 1979 in Ctenochromis by having no abrupt size transition between very small chest scales and larger ventrolateral anterior flank scales vs. abrupt size transition of scales sizes and by having a fully scaled chest vs. naked areas on chest in C. pectoralis .

From Astatoreochromis Pellegrin, 1904 both new taxa can be distinguished by having fewer dorsal fin spines 14–15 ( Palaeoplex ) / 15–16 ( Lufubuchromis ) vs. 16–20, and by having fewer anal fin spines 3 vs. 3–7 ( Banyankimbona et al. 2013). From haplochromine cichlids placed by Greenwood (1979) in Thoracochromis both new taxa can be distinguished by having no abrupt size transition between very small chest scales and larger ventrolateral anterior flank scales vs. an abrupt size transition of scales sizes in these taxa ( Greenwood 1979). Further, Palaeoplex and Lufubuchromis can be distinguished from haplochromine cichlids placed by Greenwood (1979) in Astatotilapia Pellegrin, 1904 and from Haplochromis Hilgendorf, 1888 by missing true ocelli on the anal fin; and further from Greenwood´s Astatotilapia by having more total gill rakers 12–17 ( Palaeoplex ) / 10–12 ( Lufubuchromis ) vs 8–9 ( Greenwood 1979) and from Haplochromis by having fused hypuralia 1+2 (in Lufubuchromis hypuralia 1+2 are either fused or fused with distinctly visible suture) and 3+4 vs. non fused. From members of the megadiverse haplochromine Lake Malawi radiation they can be distinguished by the absence of any ocellate or non-ocellate anal fin mark, whether round or longitudinally arranged along anal fin rays vs. present (at least in most genera; Konings 2007, Eccles & Trewavas 1989).

Palaeoplex and Lufubuchromis are distinguished from members of the serranochromine lineage (sensu Greenwood 1993) by occurrence of ctenoid scales above the lateral line (Supplementary Fig 2 . & 3 ), despite the fact that most scales are cycloid in these taxa) vs. cycloid scales above lateral line in serranochromines; and by the complete absence of non-ocellated anal fin markings vs. present in serranochromines.

Both new taxa are distinguished from Haplochromis vanheusdeni Schedel, Friel & Schliewen 2014 by having fewer dorsal fin spines, i.e. 14–15 ( Palaeoplex ) / 15–16 ( Lufubuchromis ) vs. 16–17; further H. vanheusdeni features true ocelli on the anal fin ( Schedel et al. 2014). Finally, the two genera are distinguished from Orthochromis indermauri Schedel, Vreven, Katemo Manda, Abwe, Chocha Manda & Schliewen 2018 by having fewer dorsal fin spines 14–15 ( Palaeoplex ) / 15–16 ( Lufubuchromis ) vs. 17–18.

Figures

FIGURE 2. PCA scatter plots based on 23 meristic values; species score limits visualized as convex hulls. PC I vs PC II for all examined specimens (N = 203). PC I explain 37.53 % of the variance and PC II explains 12.17 %.

FIGURE 3. Palaeoplex palimpsest sp. nov. A. holotype, alive B. holotype (ZSM 47492), 143.3 mm SL; Zambia, Luongo River C. radiograph of holotype

FIGURE 4. Female and type locality of Palaeoplex palimpsest sp. nov. A. female paratype alive B. same individual (ZSM 44438, ID: DRC-2012-/3649, 85.3 mm SL) C. Type locality of Pa. palimpsest, Luongo River (21.09.2015, Fenton P. D. Cotterill)

FIGURE 6. Lufubuchromis relictus sp. nov. A. holotype, alive B. holotype (ZSM 47494), 77.8 mm SL; Zambia, Mululwe River, trib. to Lufubu River C. radiograph of holotype

FIGURE 7. Female and type locality of Lufubuchromis relictus sp. nov. A. female paratype alive B. same individual (ZSM 44312, ID: DRC-2012-/3248, 56.7 mm SL) C. Type locality of L. relictus, rapids on the Mululwe River close to Mululwe Village (05.09.2015, F.D.B. Schedel).

FIGURE 8. Pharyngeal jaws and overview of oral jaws of Lufubuchromis relictus sp. nov. A. Lateral view of the lower pharyngeal jaw of L. relictus (Paratype; ZSM 44535, ID: DRC-2012/3897, 54.7 mm SL) B. Dorsal view of the same lower pharyngeal jaw C. Arrangement and morphology of the oral jaw teeth (Paratype, ZSM 44526, ID: DRC-2012/3884, 93.2 mm SL).