| Diagnosis: |
Dorsal spines (total): 12-13; Dorsal soft rays (total): 11-13; Anal spines: 3-3; Anal soft rays: 7-9; Vertebrae: 27-28. Diagnosis: Ptychochromis ernestmagnusi is a Ptychochromis exhibiting the eastern-type palatine morphology and is further distinguished from all congeners except P. grandidieri, P. loisellei, P. makira and P. curvidens by an anterior displacement of the first supraneural such that it overlies the dorsoposterior margin of the supraoccipital (Ref. 83427). Among eastern group Ptychochromis, P. makira shares with P. ernestmagnusi the possession of supraneurals with a characteristically flattened dorsal profile, which is interpreted here as a synapomorphy uniting these two geographically proximate species; also shared with P. makira is the presence of strong, paired, lateral barring as a prominent component of pigmentation patterning; however, P. makira can be distinguished by distinctively V-shaped lateral flank bars, whereas in P. ernestmagnusi the bars are oriented vertically; Ptychochromis ernestmagnusi is further distinguished from P. makira by conspicious iridescent spangling on the flank and dorsal fin near its base, dusky grayish-green base colouration vs. whitish, four lachrymal laterosensory foramina vs. three, and a total of seven infraorbital bones vs. six (Ref. 83427).
Description: Moderately deep bodied and laterally compressed; dorsal body profile convex, becoming significantly more so in larger specimens; ventral body profile weakly to moderately convex; lateral snout outline straight in smaller specimens, and becoming weakly curved, convex, in larger individuals; predorsal profile moderately to strongly convex from mid-orbit to dorsal-fin origin, becoming more pronounced in larger specimens and creating weak 'nuchal hump'; supraoccipital crest prominent in lateral viewand conspicuously deep bodied in larger individuals; caudal peduncle short, deep, and laterally compressed (Ref. 83427). Oral jaws isognathous and small; oral dentition bilaterally symmetrical and bicuspid, with moderately to well-developed distally expanded and slightly recurved cusps; outer row teeth of both premaxilla and dentary enlarged relative to teeth of inner rows and graded in size posterolaterally; outer row teeth procumbently implanted in rostral portion of lower jaw, and oriented vertically elsewhere; outer row teeth in upper jaw more or less vertically oriented; upper jaw with three or four rows of teeth anteriorly and tapering to single row posteriorly; lower jaw with three rows of teeth rostrally, and tapering to single row posteriorly; although smaller, inner rows of teeth on both premaxilla and dentary of same morphology as those of respective outer row; dentition covers about anterior 2/3 of dentary and nearly entire surface of premaxillary arcade (Ref. 83427). Origin of dorsal fin located well anterior to vertical through pectoral-fin insertion; origin of pelvic fin located considerably posterior to vertical through pectoral-fin insertion; dorsal fin with XII-XIII spines and 11-13 soft rays; anal fin with III spines and 7-9 soft rays; first anal-fin spine conspicuously short, whereas second and third spines elongate and more or less similar in length; distal margins of soft dorsal and anal fins becoming produced and tapered in larger specimens; posteriorly margins reaching to about caudal-fin origin in smaller individuals and extending well beyond origin in larger specimens; pectoral fin elongate, deep bodied and paddle-like; becoming tapered distally; adpressed pelvic fin terminating well before anal-fin origin in smaller specimens, and extending to about anal-fin origin in larger individuals; caudal fin emarginate, trailing margins of upper and lower lobes becoming at most weakly produced in larger individuals (Ref. 83427). Flank squamation comprised of large, regularly imbricate, weakly ctenoid scales; scale margins becoming progressively more ctenoid posteriorly on flank; ctenoid scales extend from about dorsal-fin origin dorsal to upper branch of lateral line and somewhat posterior to pectoral-fin base below upper lateral line, to proximal portion of caudal fin; scales on anterior portion of nape and throughout head region cycloid; scales on opercle and subopercle cycloid; cheek scales cycloid and comprising four rows; fourth row frequently poorly developed and comprising few scales; snout, lachrymal, and anterior portion of interorbital region to about level of mid-orbit asquamate; anterior chest scales somewhat reduced in size and embedded; scales extending onto caudal fin reduced in size and ctenoid anteriorly, markedly smaller and cycloid posteriorly; pored scales of lower branch of lateral line frequently extending onto caudal fin for one or two rows; lateral-line scales with well-developed canals, and numbering 34-37; four or five scales rows between bases of pectoral and pelvic fins; four to six scales in diagonal from upper branch of lateral line to dorsal-fin origin; no scale rows extending onto dorsal- and anal-fin membranes proximal to base of fins (Ref. 83427). Total vertebral count 27-28, with formulae of 13+14, 13+15, and 14+14 precaudal and caudal vertebrae, respectively (Ref. 83427). Lower pharyngeal jaw robust with interdigitating suture on posteroventral margin; dentition on lower pharyngeal jaw and upper pharyngeal jaw comprised of numerous, closely set, strongly hooked and bicuspid teeth; cusps on lower pharyngeal jaw teeth better developed posteriorly; posteromedially on both lower pharyngeal jaw and third pharyngobranchial toothplate, dentition becoming robust and molariform; other teeth of these elements hooked and bicuspid; expansive second pharyngobranchial toothplate bearing five or six rows of well-developed, hooked and bicuspid teeth; two or three rows of hooked and bicuspid teeth present on 'free' second epibranchial toothplate; fourth upper toothplate covered with numerous, closely-set rows of smaller hooked and bicuspid teeth; teeth becoming progressively smaller and much less well developed posteriorly; strong concavity and associated sickle-like prong present on caudomedial margin of fourth upper toothplate; dorsal surface of fourth ceratobranchial elements bearing numerous robust, laterally expanded, toothplates; fourth ceratobranchial toothplates confluent with outer row gill rakers of these elements; dentition on fourth ceratobranchial toothplates unicuspid and more or less conical to weakly hooked and bicuspid laterally, and becoming progressively more strongly hooked and bicuspid medially; contralateral fourth ceratobranchial elements bearing strong concavity and associated prong on medial margin (Ref. 83427). Eleven or 12 relatively elongate gill rakers arrayed along lower limb of first arch, excluding raker in angle of arch; lower limb rakers of first gill arch denticulate dorsomedially, bearing numerous conical to weakly hooked and bicuspid teeth; nine weakly developed and triangular epibranchial gill rakers; remaining gill arches bearing short, robust, and strongly laterally expanded rakers; these rakers strongly denticulate dorsally, bearing numerous elongate and conical to weakly hooked and bicuspid teeth (Ref. 83427).
Colouration: Colouration in life: overall uniform greenish base colouration with a dusky gray overlay, not notably darker dorsally than ventrally; many scales bearing a small, conspicuous iridescent spot along posterior scale margin; pigmentation pattern composed of five or six prominent midlateral blotches intersected by six to eight less strongly pigmented vertical bars; nape dark gray, snout and cheek dusky grey, and gular region black; fins uniformly dark blackish-gray, with some small iridescent spots proximally in soft dorsal; pectoral fin hyaline (Ref. 83427). Colouration in preservation: ground colouration reddish-brown, slightly paler ventrally than dorsally; traces of iridescent spangling present, particularly in larger specimens, and most evident ventrally on flank; pigmentation pattern consisting of five or six prominent midlateral blotches with significantly paler intersecting vertical bars retained in preservation; most posterior blotch, located on caudal peduncle, significantly paler than others; fins pale reddish-brown, trailing margins of soft anal and dorsal fins blackish; pectoral fin hyaline; pelvic fin pale reddish-brown, and becoming charcoal to blackish distally; anterior interorbital region, snout, and lachrymal dark gray; lower lip creamy brown; gular region dark grayish-black (Ref. 83427). |
