| Diagnosis: |
Dorsal spines (total): 14-15; Dorsal soft rays (total): 10-12; Anal spines: 3-3; Anal soft rays: 7-9; Vertebrae: 27-30. Diagnosis: Palaeoplex palimpsest differs from Pseudocrenilabrus multicolor by having more abdominal vertebrae, 14-15 vs. 13, and more scales on the horizontal line, 28-31 vs. 26-27; from Ps. nicholsi by having more scales on the horizontal line, 28-31 vs. 25-26, more total gill rakers, 12-17 vs. 10-11, more abdominal vertebrae, 14-15 vs. 12-13, and total vertebrae, 27-30 vs. 25-26; from Ps. pyrrhocaudalis by having more abdominal vertebrae, 14-15 vs. 12-13; it is distinguished from Ps. philander philander by more abdominal vertebrae, 14-15 vs. 12-13; it is distinguished from Ps. philander dispersus and from several Pseudocrenilabrus populations of yet undefined taxonomic status by having more abdominal vertebrae, 14-15 vs. 13; in addition Palaeoplex palimpsest has more scales on the horizontal line, 28-31 vs. 26-27 than Ps. philander dispersus, and from the putatively new species Pseudocrenilabrus sp. "Upper Kalungwishi" it is distinguished by having more total vertebrae, 27-30 vs. 26 (Ref. 122072). From Orthochromis machadoi it is distinguished by having comparatively large scales on the chest vs. partly scaleless chest, with deeply embedded minute scales; moreover, Palaeoplex palimpsest is distinguished from O. machadoi by having a distinctively longer last dorsal fin spine, 14.7-18.6% of standard length vs. 10.1-14.6%, fewer dorsal fin spines, 14-15 vs. 16-17, and by the position of the pterygiophore supporting last dorsal-fin spine at vertebral count, 13-14 vs. 15-16 (Ref. 122072). Palaeoplex palimpsest is distinguished from Orthochromis kalungwishiensis, O. luongoensis, O. katumbii, and O. mporokoso by having fewer dorsal fin spines, 14-15 vs. 16-19, and by the position of the pterygiophore supporting the last dorsal-fin spine, vertebral count 13-14 vs. 15-18, and by having fewer total vertebrae albeit with overlap, 27-30 vs. 30-33; further, Palaeoplex palimpsest is distinguished from these northern Zambian Orthochromis by having comparatively large and well-developed scales on belly and chest vs. small to minute scales, sometimes with deeply embedded chest scales; further, adult males of Palaeoplex palimpsest feature a large orange Pseudocrenilabrus blotch at the distal end of the anal fin which is absent in the northern Zambian Orthochromis species (Ref. 122072).
Description: A rather deep bodied species, body depth 28.9-36.0% of standard length, with maximum body depth slightly behind palvic fin origin, decreasing towards caudal peduncle, dorsal margin of caudal peduncle roughly on level with dorsal margin of orbit (Ref. 122072). Ratio caudal peduncle length to depth 1.2-1.8; head length about one third of standard length (Ref. 122072). Adult males with a slightly concave upper head profile; females with a straight to slightly curved upper head profile; no prominent nuchal gibbosity (Ref. 122072). Jaws isognathous to slightly retrognathous; posterior tip of maxilla reaching slightly behind nostril; lips not noticeably enlarged or thickened (Ref. 122072). Anterior jaw teeth of outer rows of upper and lower jaw subequally bicuspid to subequilaterally bicuspid and closely set; towards corner of mouth, teeth are increasingly smaller and more widely set and might become unicuspid; bicuspid teeth are slightly recurved and without or with a minimally expanded brownish crown; cusps only slightly compressed and blunt, with a moderately narrow cusp gap; neck moderately slender; outer tooth row of upper jaw with 21-57 teeth, of lower jaw with 17-51 teeth for specimens less than 143 mm standard length; larger specimens have incrementally more teeth; one to four inner upper and lower jaw tooth rows with small tricuspid teeth (Ref. 122072). Lower pharygeal bone about as wide as long, width of lower pharyngeal jawbone 95-103% of pharyngeal jaw length; dentigerous area of lower pharyngeal bone about 0.6-0.7 times length of lower pharyngeal bone length, with 21-30 teeth along posterior margin of dentigerous area; teeth in sagittal series 7-11, molariform; lateral anterior pharyngeal teeth bevelled to pronounced to moderately slender; those of posterior row larger than anterior ones, bevelled, minor cusp not well developed; largest teeth, excluding molariform teeth of sagittal series, are located centrally in posterior tooth row whereas smallest teeth are found in the posterior corners of dentigerous area (Ref. 122072). Total gill rakers 13-17 with 2-4 epibranchials, one, rarely two, in angle, and 9-12 ceratobranchial rakers; anteriormost ceratobranchial gill rakers smallest; gill rakers slender to broad and unifid, sometimes of anvil shape to bifid 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 slightly decreasing in size and more slender than ceratobranchial gill rakers (Ref. 122072). Dorsal fin with 14-15 spines and 10-12 rays; first dorsal-fin spine shortest; dorsal-fin base length between 51.2-57.3% of standard length; posterior end of dorsal fin reaching caudal fin base or ending slightly before, in females, or reaching behind caudal-fin base, in adult males; posterior tip of anal fin reaching caudal-fin base or ending slightly before; caudal fin outline rounded to subtruncate and composed of 26-30 rays, 16 principal caudal-fin rays and 10-14 procurrent caudal-fin rays; anal fin with 3 spines, 3rd spine longest, and 7-9 rays; anal-fin base length between 16.0-20.6% of standard length; pectoral fin with 13-16 rays; pectoral-fin length between 19.1-27.9% of standard length; longest pectoral ray, 4th or 5th ray counted from dorsal margin, ending slightly before level of anus; pelvic fin with one spine and 5 rays; pelvic fin base slightly further, approximately 1.5-2 times flank scale width, posterior of pectoral fin base; longest pelvic-fin ray ending behind anterior origin of anal fin base, especially in males, or ending slightly before, especially in females; adult males with moderately elongated 1st pelvic fin ray (Ref. 122072). Two separate lateral lines; flank and dorsum covered with comparatively large cycloid or weakly ctenoid scales; cycloid scales of belly slightly smaller than flank scales; chest scales cycloid and smaller than belly scales, smallest behind branchiostegal membrane; chest to flank transition with slightly larger cycloid or weakly ctenoid scales; snout scaleless; medium sized interorbital scales cycloid; anteriormost scales partially embedded in skin; nape and occipital region with slightly smaller cycloid scales compared to flank scales; cheek covered with 2-4 scale rows of small to medium sized cycloid scales; one cycloid scale between posterior orbital margin and preoperculum; operculum covered with cycloid scales of variable size, some almost size flank scales; opercular blotch squamated to variable extent; posteriormost margin always scaleless; three to five scales on horizontal line starting from anterior edge operculum to postero-dorsal edge operculum; scales on upper lateral line 16-24, lower lateral line 10-14 scales and horizontal line with 28-31 scales; upper and lower lateral lines separated by two rows of scales; five to nine scales between dorsal-fin origin and upper lateral line; 2-4 scales between origin last dorsal-fin spine and upper lateral line; anterior caudal fin part covered with 2-4 ill-defined vertical columns of small cycloid scales including 0-2 pored scales; scaled area extending posteriorly to approximately 28-42% caudal fin length with minute, interradial scales; specimens from the Luongo River with 18-20 scales around caudal peduncle, specimens from Kalungwishi River with 16-18 scales around caudal peduncle (Ref. 122072). Vertebral column with 27-29, rarely 30, total vertebrae, excluding urostyle, with 14-15 abdominal vertebrae and 13-15 caudal vertebrae; pterygiophore supporting last dorsal-fin spine inserted between neural spines 13th and 14th vertebra, counted from anterior to posterior, or 14th and 15th vertebra; pterygiophore supporting last anal-fin spine inserted between ribs of 15th vertebra and haemal spine of 16th vertebra or between haemal spines of 15th and 16th vertebra, rarely between haemal spines of 16th and 17th vertebra; one predorsal bone present; hypuralia 1 + 2 and hypuralia 3 + 4 always fused into single, sutureless unit (Ref. 122072).
Colouration: In life, pronounced sexual dimorphism present; sexually mature males with characteristic colouration pattern of metallic greenish to turquoise flanks and caudal peduncle, lower lip whitish with turquoise to greenish gleam and deep black pelvic fins (Ref. 122072). In life: body ground colouration olive; dorsum olive to pale brownish, flank and caudal peduncle greenish to turquoise; most flank and caudal peduncle scales with greenish metallic gleam, limited to posterodorsal scale margin, and continuous with neighbouring upper and lower scale; resulting pattern giving impression of shiny oblique bars across flank; flank scales posterior of head, first on to two rows, and chest golden to greenish; ventral part of chest blackish, some scales with greenish gleam, belly whitish to beige; in large adult males a greyish midlateral band can be present, but mostly faint and hardly visible; between 7 and 9 light greyish vertical bars, but mostly faint or completely absent; no distinct caudal fin spot; iris brownish with whitish patches; dorsal head surface and ethmoidal area olive to brownish; cheek olive with greenish to golden gleam, preoperculum golden; operculum with golden-orange to greenish gleam, blackish opercular spot present but might be overlain by a metallic gleam; a faint greyish lachrymal stripe present; upper lip olive with greenish gleam, lower lip whitish with turquoise to greenish gleam, especially at corner of mouth; branchiostegal membrane greyish to turquoise; dorsal fin membrane olive to brownish; dorsal fin lappets of spinous part deep black, first four spines with largest fin lappets, black dorsal fin lappets delineated by a narrow redish submarginal band from the fifth dorsal fin spine; soft rayed part of dorsal-fin membrane with small transparent to whitish maculae organized in loose oblique rows; anal fin membrane olive to brownish, whitish to hyaline distally, with irregularly set transparent to whitish maculae; orange Pseudocrenilabrus blotch on posterior margin soft rayed part anal fin, proximal side outlined with narrow whitish band; caudal fin membrane olive to yellowish; becoming less intensively coloured towards margin, with loosely set vertical rows of transparent to whitish maculae; pectoral fin membrane transparent, pectoral fin rays olive; pelvic fin membrane blackish (Ref. 122072). Females less colourful, without prominent green, gold or turquoise gleam; body primary colouration grey to olive; flank, caudal peduncle and chest with silvery gleam; chest and belly white to beige; no midlateral band visible, 7 to 9 light greyish vertical bars, but mostly faint; iris brown with whitish patches; cheek silvery; operculum silvery with patches of golden gleam; opercular spot black with gold metallic gleam; a faint grey lachrymal stripe; lips white to grey; branchiostegal membrane white to grey; dorsal fin membrane as in males; anal fin yellowish, without transparent or white maculae and without Pseudocrenilabrus blotch; pectoral fins transparent, pectoral fin rays yellow to olive; caudal fin and pelvic fin membrane yellowish (Ref. 122072). Colouration in alcohol: pigmentation and melanin patterns similar to live specimens, but due the preservation specimens lost original colouration, rendering especially melanin patterns more intense than in live specimens; overall body colouration brownish; chest in females white to beige, in males comparatively dark; operculum grey to brown; opercular spot dark brown to black; branchiostegal mebrane dusky in males and beige in females; large adult males with a faint brownish midlateral band along the horizontal line, vertical bars appear to be missing; females and small males either with or without any visible melanin pattern on flank, or with 6 to 9 faint vertical bars; vertical bars in subadults more pronounced; dorsal fin membrane grey to brown, dorsal fin lappets blackish; anal fin brown to grey with transparent maculae; Pseudocrenilabrus blotch whitish or faded; anal fin of females greyish; pelvic fin blackish in males and beige to greyish in females (Ref. 122072). |