Aphyosemion teugelsi, Van, Jouke R., Zee, Der & Sonnenberg, Rainer, 2010

Van, Jouke R., Zee, Der & Sonnenberg, Rainer, 2010, Aphyosemion teugelsi (Cyprinodontiformes: Nothobranchiidae), a new species from a remote locality in the southern Democratic Republic of the Congo, Zootaxa 2724, pp. 58-68 : 61-66

Aphyosemion teugelsi , sp. nov.

( Figs. 4–6 , Tables 1–3 )

Holotype. MRAC 62053, male, 24.2 mm SL; Democratic Republic of Congo, Bandundu Province, Lukula Creek, 10 km north of Panzi, (7° 07’ S, 17° 57’ E), 779 m altitude, southwestern Congo basin, M. Bequaert, 22 February 1939.

Paratypes. MRAC 62054–57, 3 females, 16.5–19.5 mm SL, and 1 male, 20.3 mm SL, collected with the holotype. MRAC 62058–60, 1 damaged female and 2 juvenile males, collected with the holotype, not measured.

Diagnosis. Aphyosemion teugelsi is placed within the Nothobranchiinae and Aphyosemina by the open frontal or nasal neuromast system with two separate grooves and the preopercular neuromast system with 6 pores. A closer relationship with Aphyosemion and not with Fundulopanchax is indicated by the number of circumpenduncular scales (11 or 12), and the more posterior placement of the dorsal fin relative to the anal fin.

Aphyosemion teugelsi is distinguished from all other species of the subgenus Aphyosemion by the more anterior insertion of the dorsal fin over the anal fin (D/A 6–8 versus D/A 8–13) and the longer base of the dorsal fin (13.8–15.3 % SL in A. teugelsi versus 8.6–12.1 % SL in the subgenus Aphyosemion ). It differs from all species of the subgenus Aphyosemion in having a larger head (head length 29.3–32.0 % SL in A. teugelsi versus 18.9–27.8 % SL in Aphyosemion ), and a larger eye diameter (9.1–10.3 % SL in A. teugelsi versus 6.9–8.7 % SL in Aphyosemion ). Aphyosemion teugelsi has a higher and more convex back then the species of the subgenus Aphyosemion (dorsal height in A. teugelsi is 8.0–12.5 % of the length of the spinal column versus 6–10 % in Aphyosemion ).

Males of A. teugelsi are distinguished by members of the subgenus Aphyosemion except A. congicum ( Fig. 2 ) and ‘A.’ ferranti by the absence of fin streamers on the edges of the caudal fin. With the exception of A. congicum , ‘A.’ labarrei , ‘ A.’ ocellatum, and ‘ A.’ passaroi, A. teugelsi males can be distinguished from other Aphyosemion males by the dark brown, in live most probably black, margin of all fins versus fins with a light blue, white, yellow, orange, or reddish margin.

Males can be distinguished from A. congicum populations from the adjacent Kwango basin by dark fin margins in all fins versus dark margin only in unpaired fins; dorsal fin with a dark margin and centre with spots versus almost completely black and, if with spots, only on the fin base; anal fin with broad black margin in A. teugelsi versus very narrow or no black margin in A. congicum ; caudal fin without spots in A. teugelsi and spotted in A. congicum ; pectoral fin with black margin in A. teugelsi versus white, light yellow, or bluish margin in A. congicum . Aphyosemion teugelsi can be distinguished from ‘ A.’ labarrei by several characters: flanks with a small number of small light spots, probably red in live, on anterior side in male versus a dense pattern of large red spots, forming an irregular band in ‘ A.’ labarrei , and by the following scale counts: lateral line scales 28 or 29, circumpenduncular scales 11 or 12 in A. teugelsi versus 30–32 lateral line and 13 or 14 circumpenduncular scales in ‘ A.’ labarrei .

From the two species of the ‘ Aphyosemion’ coeleste species group, ‘ A.’ ocellatum and ‘ A.’ passaroi, A. teugelsi can be separated by the absence of a dark blotch on mid of side slightly posterior to the insertion of pectoral fin versus presence of a blotch in ‘ A.’ ocellatum, the black margin on upper and lower border of caudal fin versus completely dark bordered caudal fin in ‘ A.’ passaroi, and from both species by the presence of traces of red dots in nearly regular rows, the dark margin of the pectoral fin, and extended posterior dorsal and anal fin rays versus nearly complete absence or irregular distribution of red pigmentation on side, no dark pectoral fin borders, and only slightly extended posterior dorsal and anal fin rays from both species.

Description. See Figures 4–6 for general appearance and Tables 1–3 for morphometric and meristic data of the type series. Aphyosemion teugelsi shows strong sexual dimorphism, males more colourful, unpaired fins larger, dorsal and anal fin with posterior fin rays extended. A slender, laterally slightly compressed species; dorsal profile slightly convex, greatest body depth approximately at pelvic fin. Ventral profile slightly convex from head to end of anal fin, concave on caudal peduncle. Snout slightly rounded, mouth directed upwards, lower jaw very robust and longer than upper jaw. Dentary bears an outer row of large and inner irregular rows of smaller unicuspid, curved teeth; the premaxilla bears some larger and several smaller unicuspid and curved teeth.

Frontal (after Scheel 1968) or nasal (after van Bergeijk & Alexander 1962) neuromasts in two separated grooves, the preopercular canal with six pores.

Scales cycloid, entirely scaled except ventral surface of head; frontal squamation of G-type; scales on midlongitudinal series 28 or 29, with 2 or 3 scales posterior to the hypural plate; 7 or 8 transversal scales, 11 or 12 scales around the caudal peduncle.

Small dorsal fin with 10–13 fin rays, first dorsal fin ray inserts above the 6–8th anal fin ray; anal fin with 14 or 15 rays; posterior 4 or 5 dorsal and anal fin rays elongated in males, even in juveniles of 13.5 and 14 mm SL. Caudal fin rounded, 23–25 rays, no extensions on upper and lower fin rays. Pectoral fin with 14 or 15, pelvic fin with 5 or 6 rays. Male paratype with 29 vertebrae, 14 with haemal spines.

dorsal fin rays 10 (3*), 11 (3), 13 (1)

anal fin rays 14 (1), 15 (6*)

D/A +6 (2), +7 (4*), +8 (1) caudal fin rays 23 (2*), 24 (2), 25 (3)

pelvic fin rays 5 (6), 6 (1*)

pectoral fin rays 14 (4*), 15 (3)

lateral line scales 28 (5), 29 (2*)

transversal row scales 7 (4*), 8 (3)

circumpenduncular scales 11 (1), 12 (3*)

Colour in ethanol and approximation of live colouration. Males ( Fig. 4–6 ). Flanks light brown with abrupt transition to light ventral side. Twenty to thirty small light spots mainly concentrated on anterior flanks in interrupted rows. In comparison with other species, of which live and preserved colour pattern is known, former red pigmentation in live specimens turned into light areas in formalin preserved specimens.

All paired and unpaired fins bordered with a dark brown margin; dorsal fin with small light spots, which were in live fish probably red, on darker background. Anal fin transparent, no spots, with broad dark margin. Caudal fin transparent with broad dark upper and lower margins, pectoral and pelvic fins transparent with narrow dark margins. From comparison with other species, dark margins in preserved specimens usually correspond to dark brown to black margins in live colouration.

Females ( Fig. 5 ). Flanks light brown without markings except for the dark scale edges, forming a reticulated pattern. All unpaired fins and pelvic fins completely covered with a dense pattern of very small dark spots. Pectoral fins completely transparent.

Aphyosemion . Abbreviations used in the table: CAS = A. castaneum , CHR = A. christyi , COG = A. cognatum , CON = A.

congicum , LEF = A. lefiniense , MEL = A. melanopteron , POL = A. polli , TEU = A. teugelsi , E = eye diameter, I = inter

orbital width, BD = body depth, HL = head length, HW = head width, pD = pre dorsal fin distance, pA = pre anal fin

distance, DB = dorsal fin base, AB = anal fin base, CD = caudal peduncle depth, sd = standard deviation.

species location sex SL E I BD HL HW pD pA DB AB CD

COG Z 91/3, 3 33.5 8.0 11.0 22.9 18.9 15.8 67.1 62.2 11.5 21.9 14.3 Kinshasa Ƥ 34.3 7.9 10.5 21.0 19.7 16.4 70.2 59.0 11.2 20.2 13.7

CHR HZ 85/14, 3 29.1 7.9 9.3 18.4 21.9 16.5 65.7 59.0 11.6 19.6 11.2 Epulu Ƥ 31.2 7.8 9.3 17.1 22.1 16.3 64.5 58.7 11.3 19.9 10.9

POL RCA 91/1, 3 36.0 7.5 10.6 22.5 23.3 17.2 68.3 59.4 12.1 21.7 13.1 Ƥ 19.4 7.7 11.9 20.8 19.8 14.0 68.3 52.1 11.5 20.0 12.3

LEF Lonna river 3 23.1 8.7 12.1 19.0 24.1 14.3 66.6 54.9 7.0 13.0 9.6 Distribution. Apyhosemion teugelsi is currently only known from its type locality, the Lukula Creek 10 km north of Panzi, a tributary of the Wamba River in the southwestern part of the Democratic Republic of Congo. This is the highest known elevation for a killifish in the Congo basin as the type locality is probably situated near the only road in this area that lies at an elevation of approximately 1000 meters. Aphyosemion teugelsi is also the southernmost occurring species of Aphyosemion s.l.

Relationship. Within the genus Aphyosemion only one species shares the broad black fin margins and an almost unspotted anal fin in males: A. congicum . Aphyosemion congicum (Type locality “ Kongo ”) and A. melanopteron Goldstein & Ricco, 1970 (Type locality unknown) are supposed to be conspecific ( Seegers, 1988), with the latter as a junior synonym. However, Huber (2007, online version www.killi-data.org) noticed a significant difference in the number of spots on the flanks. In the description of A. congicum Ahl (1924) mentioned: “whole body provided with a large number of irregularly distributed carmine red spots”. All known A. melanopteron populations show 25–40 red spots that are not considered as high numbers for Aphyosemion . Aphyosemion species can show up to 130 red spots on one flank (e. g. in A. rectogoense Radda & Huber, 1977 ). In his descriptions Ahl usually mentioned “a number of red spots” when no particular low or high numbers were meant. This suggests that in A. congicum a higher number of spots could be present than in A. melanopteron , unfortunately the type material of A. congicum did not show any traces of colour pattern remains any more. It is possible that A. congicum and A. melanopteron represent two different phenotypes of the same species but due to the lack of densely collected samples from the distribution range it can not be excluded that the two taxa represent two different species. However, both share the same pattern of dark fin margins and can be distinguished from ' A.' teugelsi by the same diagnostic characters.

'Aphyosemion' teugelsi differs from species of Aphyosemion by a more anterior position of the dorsal fin, the absence of fin streamers in the caudal fin, a more convex back, and the more robust lower jaw, therefore we exclude it at the moment from this group.

Other species with a southern distribution in the Congo basin are ' Aphyosemion' ferranti and ' A.' lujae, which are currently only known from preserved material, and their taxonomic placement is not well studied. These species have distinctive colour patterns (i.e., a horizontal dark band on rear body, and a caudal fin with spots or stripes, and no dark margins on unpaired fins) that distinguish them from the new species and none of them shows black fin margins. ' Aphyosemion' ferranti shares with 'A.' teugelsi a more robust lower jaw and the rounded caudal fin without fin extensions. However, for a final conclusion about a closer relationship of these three 'southern' species, detailed morphological and, with suitable samples, DNA studies are needed.

Currently no comprehensive and detailed comparative morphological study of the African nothobranchiids is available and for most species groups and genera robust diagnostic characters are not known. Whereas species groups are easily recovered by DNA studies ( Murphy & Collier 1999), it is often difficult to unambiguously assign preserved specimens by external morphological characters ( Scheel 1968).

In order to check phylogenetic relationships, a small sample of body tissue was collected and several extraction methods were tested to get DNA from ' A.' teugelsi . Unfortunately no detectable amount of DNA could be recovered and also PCRs attempts with primer combinations for short fragments (ca. 200–500 bp) gave no results. Therefore we hesitate here to assign ' A.' teugelsi into one of the currently established species groups, subgenera, or genera ( Sonnenberg 2007), due to its divergent morphology, and the absence of clear diagnostic characters.

Etymology. The species is dedicated to the late Guy Teugels (Royal Museum for Central Africa, Tervuren, Belgium) who died at 50 years of age in 2003. Guy was renowned worldwide for his contribution of the knowledge of African freshwater fishes, especially for his expertise in clariid catfishes, his favorite group. He was not only characterized by an impressive scientific productivity but also by his affection for the African continent and its people. Guy was an enthusiastic coach for the first author at the Zoology department of the museum for many years.

Figures

FIGURE 2. Aphyosemion congicum, male, 39 km east of the Lufimi River, collection locality Z 82 - 17, F 3 of the specimens collected in the wild, not preserved. Photographed by T. Woeltjes.

FIGURE 4. Aphyosemion teugelsi, sp. nov., male, 24.2 mm SL, MRAC 62053, holotype.

FIGURE 5. Aphyosemion teugelsi, sp. nov., above male, 20.3 mm SL, below female, 19.5 mm SL, MRAC 62054 – 62057, paratypes.

FIGURE 6. Sketch of the approximated colour pattern of Aphyosemion teugelsi, sp. nov. Drawing by R. H. Wildekamp.