Epiplatys atratus, Van Der Zee, Jouke R., Mbimbi Mayi Munene, José J. & Sonnenberg, Rainer, 2013

Van Der Zee, Jouke R., Mbimbi Mayi Munene, José J. & Sonnenberg, Rainer, 2013, Epiplatys atratus (Cyprinodontiformes: Nothobranchiidae), a new species of the E. multifasciatus species group from the Lulua Basin (Kasaï drainage), Democratic Republic of Congo, Zootaxa 3700 (3), pp. 411-422 : 413-416

Epiplatys atratus , new species

( Figs. 3 & 4 , Tables 1 & 2 )

Holotype. AMNH 253838, male, 40.7 mm SL, Democratic Republic of Congo, Kasaï Occidental, Lulua River Basin, Minkidimbua River, village Kakunku, 06° 06.23’ S, 22° 42.49’ E, collected by J. J. Mbimbi Mayi Munene, 29 January 2010.

Paratypes. Total 22 specimens; AMNH 253839, 3 males, 35.3–36.4 mm SL, 1 female, 30.0 mm SL, collected with the holotype; AMNH 257029, 5 males, 26.2–39.1 mm SL, collected with the holotype; AMNH 253840, 2 females, 35.0–38.0 mm SL, Democratic Republic of Congo, Kasaï Occidental, Lulua River Basin, Musangu River, village Kantumanga, 06° 00.32’ S, 22° 31.22’ E, collected by J. J. Mbimbi Mayi Munene, 27 January 2010; AMNH 253841, 4 males, 33.9–42.7 mm SL, Democratic Republic of Congo, Kasaï Occidental, Lulua River Basin, Lunyenga River, village Kamuandu, 06° 03.54’ S, 22° 39.10’ E, collected by J. J. Mbimbi Mayi Munene, 28 January 2010; MRAC B2-26-P-1–2 (ex AMNH 252452), 2 males, 36.7–41.5 mm SL, Democratic Republic of Congo, Kasaï Occidental, Lulua River Basin, Musangu River, village Kantumanga, 06° 00.32’ S, 22° 31.22’ E, collected by J. J. Mbimbi Mayi Munene, 27 January 2010; BMNH 2012.8.24.1–2 (ex AMNH 252452), 2 males, 39.5–41.2 mm SL, Democratic Republic of Congo, Kasaï Occidental, Lulua River Basin, Musangu River, village Kantumanga, 06° 00.32’ S, 22° 31.22’ E, collected by J. J. Mbimbi Mayi Munene, 27 January 2010; AMNH 252457, 2 males, 37.0– 37.4 mm SL, Democratic Republic of Congo, Kasaï Occidental, Lulua River Basin, Lukumbi Kumbi River, village Kantumanga, 06° 00.16’ S, 22° 31.32’ E, collected by J. J. Mbimbi Mayi Munene, 27 January 2010; AMNH 252458, 1 male, 36.5 mm SL, Democratic Republic of Congo, Kasaï Occidental, Lulua River Basin, Luankadi River, Mikalayi village, 05° 58.06’ S, 22° 20.32’ E, collected by J. J. Mbimbi Mayi Munene, 22 June 2010.

Diagnosis. Epiplatys atratus ( Figs. 3 & 4 ) belongs to a supragroup of species, the E. multifasciatus , ansorgii and sangmelinensis species groups, characterized by the possession of a large mouth, reaching the ventral border of the eye. It is placed in the E. multifasciatus species group and distinguished from members of the E. ansorgii species group, by the absence of a dark bar under the eye, and from members of the E. sangmelinensis group, by the presence of two dark bars on the lower jaw, which are absent in the E. sangmelinensis group. Epiplatys atratus is only known from preserved specimens, therefore the mentioned colour patterns refer to colouration in ethanol. Large males of E. atratus differ from all other Epiplatys species by the almost dark grey to black body colour. Small males and females differ from all other described Epiplatys species by having 3 narrow oblique black bars on the flanks just behind the pectoral fin. This character is shared by two other undescribed species, also from the middle Lulua River system (see Discussion).

It is distinguished from all other members of the E. multifasciatus species group by the possession of a dorsal fin inserted above anal fin ray 8–10 versus 10–13 ( Table 3 ); in large males the lobes surrounding the supra-orbital laterosensory system almost cover the groove ( Fig. 5 ) versus a completely open groove in large males of other species; from E. multifasciatus , E. mesogramma , and E. phoeniceps it is additionally distinguished by the absence of broad dark bars on the flanks and fins of males without markings versus all fins spotted, the anal fin provided with two or three dark blotches as extensions of the dark bars on the flanks. Epiplatys atratus shows only narrow dark bars on side (less then one scale broad), whereas the former species have broader dark bars (about two scales broad) and only sometimes narrow bars in between. It is further distinguished from E. c. chevalieri and E. c. nigricans by the presence of narrow vertical bars in smaller males and in females versus complete absence of vertical bars.

Description. See Figures 3 & 4 for general appearance and Tables 1 & 2 for morphometric and meristic data of the type series. Slightly compressed and deep-bodied, exhibiting marked sexual dichromatism with large adult males black without bars, females brown with up to 14 narrow dark bars, median fins in males large and unspotted, small and spotted in females. Dorsal profile slightly convex, greatest body depth approximately at level of pelvic fins. Ventral profile slightly convex from head to end of anal fin, concave on caudal peduncle. Snout pointed, mouth directed upwards and prognathous. Dentary and premaxilla with an outer row of large and several inner irregular rows of smaller recurved unicuspid teeth. Frontal (after Scheel 1968) or nasal (after van Bergeijk & Alexander 1962) neuromasts in single groove, preopercular canal with five pores. Scales cycloid, entirely scaled except on ventral surface of head; frontal squamation with the G-scale overlapping the posterior E-scales; midlongitudinal series 26–29, with 1 or 2 scales posterior to hypural plate; 12 circumpeduncular scales. Dorsal fin with 9 or 10 fin rays, first dorsal fin ray inserts above the 8th or 10th anal fin ray; anal fin with 13–14 rays; dorsal fin rays 6 or 7 and anal fin rays 8–10 elongated in males; caudal fin with 21–23 rays, no extensions of caudal fin rays.

E. atratus E. multifasciatus E. c. chevalieri E. c. nigricans Colour in preservation. Males ( Fig. 3 ). Flanks black or dark brown with sharp transition to lighter ventrum. Most scales black posteriorly and lighter anteriorly, resulting in a checkerboard-like pattern. This pattern is obscured in some, presumably dominant males, which are uniformly black or dark brown. However, some males resemble females, with a more irregular distribution of black spots on the flanks and 6–14 very narrow vertical black bars, the anterior most 3 bars are oblique and only present on ventral side of the flanks. Head almost black with the exception of the ventral part of the preopercule. Lower jaw and preopercular neuromast canals black. All fins without distinct markings. Median fins dark grey with narrow black edges, fin rays lighter then fin tissue. Pelvic fins black. Pectoral fins translucent grey, fin rays darker then fin tissue.

Females ( Fig. 4 ). Body colour similar to smaller males, with the exception of the black spots on the flanks have a lighter centre in females. These light centres are probably red in live specimens. Red pigmentation often leaves corresponding patterns of lighter areas than the body colouration after preservation (Van der Zee & Sonnenberg 2010). Median and ventral fins translucent grey, provided with elongated black spots, in caudal fin concentrated in the upper half, in anal fin black spots form a crescent shape band. Fin rays darker then fin tissue. Small black triangles at dorsal and ventral onset of caudal fin. Dorsal, anal, and ventral fins with black edges. Pectoral and pelvic fins translucent.

Distribution. ( Figs. 1 & 6 ) Epiplatys atratus is the south-easternmost species of Epiplatys . It is restricted to small tributaries in the gallery forest of the Middle Lulua River just south and southeast of Kananga, Kasaï Occidental. Epiplatys atratus is found in small (width up to 5 m), rather fast flowing rivers ( Fig. 7 ) containing acid water ( pH 4.5–6.6) with water temperatures ranging from 24.3–30.3 ° C.

Etymology. The species name, atratus , means "clothed in black", from the Latin “ater” (black), referring to adult dominant males that have an almost black appearance in ethanol.

Figures

FIGURE 1. Epiplatys multifasciatus (Boulenger, 1913), male syntype, 33.1 mm SL, MRAC 2734 – 2736, Kondué, Sankuru River Basin, Kasaï Oriental Province, Democratic Republic of Congo.

FIGURE 3. Epiplatys atratus, male holotype, 40.7 mm SL, AMNH 253838, Minkidimbua River, Lulua River Basin, Kasaï Occidental, Democratic Republic of Congo.

FIGURE 4. Epiplatys atratus, female paratype, 30.0 mm SL, AMNH 253839, Minkidimbua River, Lulua River Basin, Kasaï Occidental, Democratic Republic of Congo.

FIGURE 5. Dorsal view of the right anterior part of the head of E. atratus. A: G-scale, B: frontal neuromast system, C: mouth cleft, D: Supra-orbital neuromast system, E: eye, arrows point to the narrow opening due to large lobes.

FIGURE 6. Known collections of E. atratus, E. multifasciatus, and E. sp. “ pale ” in the middle Lulua basin.

FIGURE 7. Minkidimbua River, type locality of E. atratus. Photographed by J. J. Mbimbi Mayi Munene on 29 January 2010.

Tables

TABLE 1. Morphometric data of Epiplatys atratus, new species (H = holotype, P = paratypes: 7 males and 3 females). All measurements in percentages of standard length (SL), standard length in mm. Paratypes 1 – 4 = AMNH 253839, paratypes 5 – 6 = AMNH 253840, paratypes 7 – 10 = AMNH 253841.

H ♂	P 1♂ P 2♂	P3 ♂	P 4♀	P 5♀	P6♀	P 7♂	P8 ♂	P9♂	P10♂
Standard length 40.7	36.2 35.3	36.4	30.0	35.0	38.0	42.7	42.4	33.9	37.8
Body depth 22.4	23.2 22.9	21.7	22.0	22.8	23.7	24.6	25.0	24.2	23.8
Head length 25.1	25.1 24.9	25.5	25.6	24.6	25.5	22.7	23.8	23.0	23.8
Eye diameter 8.6	8.3 8.3	9.1	8.3	9.1	8.9	8.2	9.4	8.6	8.2
Interorbital width 14.3	13.3 13.6	14.0	14.0	13.1	14.7	13.3	13.7	13.9	13.8
Pre-dorsal length 66.8	69.0 68.3	71.2	79.0	72.0	72.6	73.0	70.6	72.6	73.5
Pre-anal length 61.7	59.7 58.6	60.4	66.0	59.1	47.9	60.4	59.9	62.2	62.9
Pre-ventral length 44.5	42.2 42.2	44.8	46.6	44.6	20.2	45.9	44.3	44.8	45.2
Dorsal fin base 12.3	11.9 11.6	13.5	9.0	11.1	10.1	12.4	12.0	13.6	13.7
Anal fin base 20.9	19.6 19.0	19.8	15.7	18.9	18.9	19.2	19.6	18.3	22.2
Caudal ped. length 20.1	20.4 21.2	21.4	18.3	19.7	20.2	22.9	22.6	20.1	20.9
Caudal ped. depth 14.3	13.5 13.3	12.6	12.3	12.9	13.7	13.3	13.4	12.1	13.8
Caudal ped. ratio 1.4	1.5 1.6	1.7	1.5	1.5	1.5	1.7	1.6	1.7	1.5

TABLE 2. Meristics of Epiplatys atratus, new species. Numbers indicate observed values; numbers in parentheses frequency of occurrence; values found for the holotype are indicated by an asterisk. Some counts could not be taken from all specimens, so the total number of observed frequencies can be below 11, which is the total number of measured specimens.

meristic count		values (frequency)
dorsal fin rays		9 (3), 10 (6*)
anal fin rays		13 (7*), 14 (3)
D/A		+8 (2*), +9 (2), +10 (6)
caudal fin rays		21 (7), 22 (3*), 23 (1)
pectoral fin rays		14 (2), 16 (3*), 17 (6)
lateral line scales		26 (1), 27 (1) 28 (5*), 29	(1)
circumpenduncular	scales	12 (9*)

TABLE 3. Morphometric and meristic data of E. atratus, new species, E. multifasciatus (types), E. chevalieri chevalieri (MRAC 77138 – 141, Kinshasa) and E. chevalieri nigricans (MRAC 73 - 23 - P- 12780 – 793, Buta; MRAC 65341 – 345, Uele) as average (left) and range (right). All measurements are given as % of SL.

standard length	38.0	35.3–42.4	29.0	26.2–34.0	38.0	33.3–40.5	33.9	31.9–35.8
body depth	23.4	21.7–25.0	20.7	17.9–22.8	23.3	20.1–24.8	21.3	19.8–23.2
head length	24.1	22.7–25.1	25.8	23.7–28.0	24.4	22.5–24.8	24.1	22.2–25.4
eye diameter	8.6	8.2–9.4	9.6	8.7–9.9	8.6	8.1–9.2	8.6	8.2–8.9
interorbital width	13.7	13.2–14.3	14.1	13.8–14.7	14.3	13.5–15.3	13.7	13.3–14.1
pre-dorsal length	71.7	66.8–79.0	74.2	71.5–77.2	76.9	73.8–79.9	76.1	73.6–78.0
pre-anal length	60.6	58.6–62.9	63.1	59.8–65.1	60.7	57.9–63.2	61.7	58.4–63.3
dorsal fin base	11.7	11.6–13.7	10.1	9.2–11.7	10.1	8.7–12.2	10.1	9.6–12.8
anal fin base	20.2	18.1–21.7	19.7	18.6–21.7	19.7	20.6–23.4	19.7	18.6–21.7
caudal ped. length	20.9	18.7–22.9	19.5	17.7–20.7	19.5	16.4–20.5	19.4	17.1–21.0
caudal ped. depth	13.3	12.0–14.3	11.6	10.7–12.8	14.8	12.9–15.6	13.3	12.9–13.7
caudal ped. ratio	1.6	1.4–1.7	1.5	1.4–1.8	1.3	1.2–1.4		1.4–1.6
dorsal fin rays		9–10		8–10		8–9		8–9
anal fin rays		13–14		13–16		12–15		14–15
D/A		8–10		10–11		11–13		12–13
Lateral lines scales		26–29		26–27		24–27		25–27