Chromaphyosemion omega, Rainer Sonnenberg, 2007

Rainer Sonnenberg, 2007, Description of three new species of the genus Chromaphyosemion Radda, 1971 (Cyprinodontiformes: Nothobranchiidae) from the coastal plains of Cameroon with a preliminary review of the Chromaphyosemion splendopleure complex., Zootaxa 1591, pp. 1-38 : 12-16

Chromaphyosemion omega sp. nov.

(Figs. 9-11)

Aphyosemion bivittatum (non Lönnberg, 1895), Scheel 1968: 117-127 (in part, distribution, morphology, taxonomy, synonymy).

Aphyosemion (Chromaphyosemion) bitaeniatum (non Ahl, 1924), Scheel 1990: 168-173 (in part, distribution, karyotypes, taxonomy).

Aphyosemion (Chromaphyosemion) splendopleure (non Brüning, 1929a), Agnèse et al. 2006 (in part, phylogeny, collection localities, taxonomy), Amiet 1987: 49, 176, plate 36, fig. 15 (in part, collection localities, color pattern), Huber 1998a: 20-21 (in part, taxonomy, distribution), 2000: 471 (in part, collection localities), Legros & Zentz 2007: 20- 21 (phylogeny), Radda & Pürzl 1982: 24-25 (in part, distribution), Radda & Pürzl 1983: 20-21 (in part, distribution) 1987: 70 (in part, distribution), Seegers 1981: 159, 161 (in part, distribution), 1986: 52-54 (in part, distribution), Wildekamp 1993: 277-279 (in part, distribution, morphology).

Aphyosemion (Chromaphyosemion) splendopleure 'Kopongo' (non Brüning, 1929a), Eberl 1996: 48-50 (color pattern, collection localities, color photo p. 49, lower picture, erroneously exchanged with the above picture), Eigelshofen 1998: 9-12 (distribution, color photo).

Chromaphyosemion sp. aff. splendopleure 'Kopongo', Sonnenberg 2000: 81, 85-86 (color pattern, distribution, color photo Nr. 4).

Holotype. ZFMK 39970 , male (31.3 mm SL), Cameroon, old road from Edea to Douala, small river Ngo Njock near the village Ndog Nyang , (03°59'12.4'' N, 10°05'50.3'' E), U. Kämpf, R. Sonnenberg and A. Tränkner leg., collection locality CMM 7.

Paratypes. ZFMK 39971-39980 (7 males, 2 females, 1 juvenile), paratopotypes, collected with holotype .

ZFMK 39981-39986 (5 males, 1 female, 1 juvenile), Cameroon, creek crossing the old road from Edea to Douala, near Bonepoupa (04°06'30.1'' N, 10°01'12.6'' E), H. Kullmann, B. Misof and R. Sonnenberg leg., collection locality C 01/62.

CENAREST, Batoke, Cameroon (1 male), same collection data as holotype .

CENAREST, Batoke, Cameroon (1 female), same collection data as ZFMK 39981-39986 .

Diagnosis. Chromaphyosemion omega is distinguished from all surrounding and closely related congeners by completely orange anal and pelvic fins without red pattern, a red submarginal and a blue marginal band, in some specimens a small greenish basal part with a row of basal dark red dots in anal fin versus incomplete orange anal fin with red markings and always blue in lower half, but above submarginal red band in C. loennbergii , greenish in C. koungueense , only partially orange with yellow or greenish anal in C. splendopleure s.l. and C. punctulatum , or with a yellow or greenish marginal band in C. splendopleure s.l. It is distinguished from all remaining Chromphyosemion species by the unique combination of color patterns.

Description. See Figures 9-11 for general appearance and Table 3 for morphometric data of the type series and for general description under C. koungueense . First ray of dorsal fin in front or above 1st or 2nd anal fin ray. Dorsal fin with 11-13 rays, anal fin with 13-15 rays. Pectoral fins extending over origin of pelvic fins, pelvic fins not or nearly reaching anal fin. Pectoral fin rays dorsally longer then ventrally.

Scales cycloid, body and head entirely scaled, except ventral surface of head. Frontal squamation of G- type, scales on mid-longitudinal series 23-26 + 2-3 on caudal fin base. Transverse row of scales above pelvic fins 8-9, circum-peduncular scale row 12-13. Open frontal neuromast system with two separate grooves, preopercular neuromast system with 6 pores.

Coloration. Live specimens. Males (Figs. 9-10). Back brownish, scales from point of greatest body height on sides dorsally metallic copper to greenish, sides between black lateral stripes pale greyish with a light blue metallic sheen, ventrally greyish to whitish, from lower head extending ventrally on sides to end of caudal more or less greyish to orange, often also on sides on caudal peduncle behind posterior end of caudal fin base. Yellowish or orange metallic blotch on opercle behind eye between lateral stripes. In fully colored males upper half of sides with metallic copper to greenish color, middle of sides light bluish and lower sides with intensive orange color. Three rows of red dots on scales extending from opercle and dissolve into irregularly distributed red dots on sides, lower row on middle of body splitting in two rows posterior to opercle.

Dorsal fin greenish or bluish-green, upper half more orange with orange fin streamer. Red dots between fin rays, on upper half of fin often fusing into streaks. Anal fin orange, sometimes basal green or bluish-green band with red dots, anal fin center usually without red markings. Submarginal band red, marginal band blue. Posterior end of fin sometimes with small extension, yellow or bluish. Caudal fin center bluish-green to hyaline orange, in lower part bordered by orange line directly extending into lower fin streamer above red submarginal band, marginal band blue. Upper margin of caudal fin with small blue band, interrupted by red markings; below orange, extending from base of caudal fin straight into upper fin streamer, often conspicuously colored yellow to orange. Red dots and streaks between fin rays. Pelvic fins similarly colored as anal fin, orange with submarginal red and marginal blue bands. Pectoral fins hyaline orange, distally darker.

Females (Fig. 11). Back brown, three dorsolateral rows of scales with metallic copper or greenish color from point of greatest body height to end of caudal peduncle. Scales with darker borders, sometimes with red dots; on sides with two parallel black stripes, between stripes pale greyish or beige, some bluish-green metallic scales on posterior sides, on lower anterior sides orange hue, ventrally light grey to whitish. Some specimens with small red dots on scales, more or less regularly in rows. Orange area on opercle between lateral stripes. All fins hyaline, coloration similar to fins of males except anal fin, greenish, at least lower half orange to yellowish. Dark or red dots in dorsal fin, dots and streaks in caudal fin, in some specimens also red dots in anal fin. Anal and caudal fins with blue marginal band, anal fin with dark red submarginal band. Pelvic fins hyaline greenish in upper half, orange in lower half with bluish margin. Pectoral fins hyaline with slightly dark pigmentation and metallic blue margin on lower distal half.

Preserved in ethanol. Males. Back and sides brown, both lateral stripes dark brown, belly beige to whitish. Scales on back and sides with dark brown border forming a reticulated pattern. Border of opercle ventrally of lower stripe dark, area below lower lip whitish to beige. Unpaired and pelvic fins hyaline greyish with dark pigmentation at fin rays, dark margin on unpaired and pelvic fins. Pectoral fins hyaline.

Females. Similar to males and juveniles. Body brownish, scales on back with dark border, belly beige to whitish. Fins hyaline greyish, slight dark pigmentation and no dark margin on anal fin.

Etymology. This species is named with regard to Chromaphyosemion alpha in the sense of alpha 'the beginning'; from Greek: omega used in the meaning of 'the end'. This is meant in relation to the relative (phylogenetic) position of both species within Chromaphyosemion with C. alpha as the basal species and C. omega as a more derived species, which is the result of a recent radiation.

Distribution and habitat. Chromaphyosemion omega is currently known from several places along the road between Kopongo / Somakek and Bonepoupa (see Map 1). Near Somakek it is found in sympatry with C. riggenbachi . The latter species also occurs in rivers within the distribution range of C. omega but extends further north, south and east of the latter. To the west and northwest, C. omega is replaced by the closely related C. koungueense . Near Bonepoupa both species are found in close vicinity between the localities Mangoule and KV 03/17 ( C. koungueense ) and C 01/62 ( C. omega ).

The type locality is a small river in the forest with a maximal depth of approximately 0.2 m and up to 3 m wide. The bottom consists of sand and gravel and lacking aquatic plants. The water temperature was 26.6 °C, air temperature 30°C, pH 6 and conductivity ~ 10µS/cm. Syntopic fishes were Epiplatys infrafasciatus , 'Aphyosemion' ahli , ' A. ' franzwerneri , Procatopus sp. and an undetermined juvenile clariid species.