Plataplochilus eliasi Walsh, de Bragança & van der Zee, 2022 |
Family: | Procatopodidae (African lampeyes), subfamily: Procatopodinae | |||
Max. size: | 4.1 cm SL (male/unsexed); 3.34 cm SL (female) | |||
Environment: | pelagic; freshwater | |||
Distribution: | Africa: Bondo River catchment, tributary of Noumbi River basin in Republic of the Congo (Ref. 125987). | |||
Diagnosis: |
Dorsal spines (total): 0-0; Dorsal soft rays (total): 12-13; Anal spines: 0-0; Anal soft rays: 16-18. Diagnosis: Plataplochilus eliasi belongs to Plataplochilus by the anterior portion of the alveolar arm of the premaxilla developed into a squared process, the dorsoposterior process of the autolapalatine directed upwards, an elliptical supracleithrum, the dorsoposterior border of the cleithrum broad and posteriorly elongated, a rectangular and anteroposteriorly elongated lachrymal, and the presence of an upper lobe extension in the caudal fin of males (Ref. 125987). It differs from all described Plataplochilus species by the unique colour pattern of adult males: the flank above the mid-longitudinal line is brownish to olive green whereas the lower half of the flank and the operculum are bright dark blue; a large, round dark blue to black spot is present on the operculum; and a broad submarginal black band is present from the origin of the anal fin to end of the caudal peduncle; Plataplochilus chalcopyrus, P. mimus, P. ngaensis and P. terveri are lacking this band and opercular spot, and have a silvery lower flank with a blueish, greenish or brownish iridescence (Ref. 125987). Plataplochilus eliasi differs from P. pulcher and P. miltotaenia by lacking a narrow longitudinal red line on the flank; the colour pattern of P. cabindae, P. micrurus and P. loemensis is not known; Plataplochilus micrurus has the largest predorsal distance of all Plataplochilus species, 73% of standard length vs. less than 64%, and a strikingly lower number of dorsal and anal-fin rays, respectivelt 6 and 12 vs. 9-16 and 14-18 in all other species, 12-13 and 16-18 in P. eliasi (Ref. 125987). Furthermore, the new species also differs from all described Plataplochilus species by having a deeper body; adult males are the deepest of all species in the genus, 38.4-42.4% of standard length vs. less than 36.2%; all other described species have more slender bodies (Ref. 125987). In addition, Plataplochilus eliasi differs from all described species except P. miltotaenia by having 12-13 dorsal fin rays, vs. 13-16 in P. miltotaenia and less than 13 in all other species; it is similar to P. miltotaenia, P. terveri and P. loemensis by having 7-8 scales in a transversal row, distinguishing it from all other congeners, which have only 6 scales; Plataplochilus eliasi is also distinguished from P. miltotaenia by having the first ray of the dorsal fin inserted above anal-fin rays 4-5, vs. 1-3 in P. miltotaenia; adult females of P. eliasi have a rather similar colour pattern to other species of the genus, but can be easily distinguished from P. miltotaenia females by lacking a narrow mid-lateral longitudinal red line (Ref. 125987). Description: Dorsal profile of body deeply convex from snout tip to end of dorsal-fin base, slightly concave to straight from end of dorsal-fin base to end of caudal peduncle; ventral profile deeply convex from lower jaw to end of anal-fin base, slightly concave to nearly straight on caudal peduncle; anterior portion of body laterally compressed, becoming more compressed behind anal-fin origin (Ref. 125987). Snout pointed, mouth directed upwards, lower jaw longer than upper jaw, posterior end of mouth just below ventral edge of eye and at the level of the midline of the lachrymal bone in the pre-orbital region (Ref. 125987). Males' anal and dorsal fins slightly pointed with straight ventral and dorsal margin, respectively; caudal in truncate, with upper lobe rays slightly extended in males; pectoral fin elliptical in both males and females; females' unpaired fins with straight ventral and dorsal margins; dorsal fin inserted posterior to mid-body in both sexes, anal fin inserted at mid-body in males and posterior to mid-body in females; dorsal fin origin at a vertical line through the 4th anal-fin ray in males; pelvic fin reaching between urogenital papilla and origin of anal fin in males, and to the urogenital papilla in females; female with enlarged left and right scale at the origin of anal fin, covering urogenital opening (Ref. 125987). Anterior portion of supraorbital system with four large pores, the central pores elongated, posterior portion trapezoidal with four small, round to ovoid pores; pre-opercular system with seven pores; pre-orbital system with four to five pores; post-orbital system closed with two pores and connected dorsally with posterior portion of supra-orbital system; mandibular canal closed, with five pores (Ref. 125987). Coulouration: Colouration in ethanol: males dorsal region of body brownish, top two scale rows with dark edges; flanks below these rows light greyish brown with a prominent crescent-shaped dark grey to black band reaching from lower jaw to pectoral fin insertion; grey along the middle portion of body, just after pectoral fin insertion to end of anal fin base; and black from region posterior to anal fin base to caudal peduncle; pre-orbital area and sub-orbital rim black; centre of operculum black; head ventral region and throat light yelowish brown; unpaired fins hyaline, with minute black chromatophores scattered over fin membranes; dorsal fin posterior rays tip black; pectoral fin hyaline; pectoral fin base dark brown to black; pelvic fins yellowish brown (Ref. 125987). Females with body predominantly light brown with darker dorsum; the crescent-shaped dark pigmentation is shorter and inconspicuous, extending from region posterior to pectoral fin insertion to caudal peduncle; lower jaw and pre-orbital region dark black, and sub-orbital rim, opercle and pectoral fin insertion yellowish brown; unpaired fins with small black spots, lacking at base of fin; paired fins hyaline (Ref. 125987). Colouration of live male specimens: dorsum and anterior dorsal part of flank, from region just posterior to head to dorsal fin origin, brownish to olive green; posterior region of flank silver; head dorsal region dark brown, posterior region light brown and with a bright cupric blotch; opercle dark black with metallic bright blue chromatophores; snout, pre-orbital region and sub-orbital rim dark black, scattered with metallic bright blue minute chromatophores; branchiostegal appendages bright yellow; ventral region of head whitish grey; ventrum bright blue from opercle posterior margin to caudal peduncle; ventral portion of flank dark metallic blue with a broad submarginal balck band from origin of anal fin to end of caudal peduncle; pectoral fins hyaline, pelvic fins yellow to orange; dorsal fin base with a yellowish-orange band, narrow anteriorly and becoming wider posteriorly, followed by a blue-grey band edged distally with a narrow black band, distal edge of fin hyaline; anal fin with narrow light bright blue-grey band at base, followed by a wide yellow band, edge of fin grey; caudal fin grey with blue to black centre inter-radials, narrow red to orange ventral and dorsal edges; pelvic fins yellow; pectoral fin hyaline (Ref. 125987). Colouration of live female specimens: dorsum dark grey; dorsal part of flanks brownish, ventrally whitish with vague dark grey band anteriorly; dorsal fin orange-red with narrow hyaline band at base and broad hyaline outer edge; anal fin hyaline with orange-red band just distal of midline of fin; caudal fin hyaline with orange-red dorsal and ventral edges; pelvic and pectoral fins hyaline; females have less distinctly darkened scale margins compared to males, or darkened scale margins are even absent (Ref. 125987). |
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Biology: | Plataplochilus eliasi is found in very shallow, clear-water creeks over diverse substrate types consisting of boulders, cobbles and pebbles with Anubias sp. and overhanging vegetation (Ref. 125987). It appears to have a strong preference for fast-flowing stream sections on steep slopes (Ref. 125987). | |||
IUCN Red List Status: | Not Evaluated (N.E.) Ref. (130435) | |||
Threat to humans: | harmless |