Astatoreochromis straeleni (Poll, 1944)

Banyankimbona, Gaspard, Vreven, Emmanuel & Snoeks, Jos, 2013, A revision of the genus Astatoreochromis (Teleostei, Cichlidae), East-Africa, European Journal of Taxonomy 39, pp. 1-21 : 13-18

Astatoreochromis straeleni (Poll, 1944)

Fig. 6

Bluelip haplo, local names: ‘Ifuro’ (common name for all haplochromine species in the Malagarazi), ‘Ikijori’ (name for all haplochromine species in the Rusizi basin) or ‘Inunge’ (used by fishermen from the Rusizi basin who distinguish this species from other haplochromine species).

Haplochromis straeleni Poll, 1944: 10 , figs 9-10.

Haplochromis vanderhorsti Greenwood, 1954: 405-413 , figs 1-3.

Astatoreochromis straeleni – Poll 1974: 100.

Astatoreochromis vanderhorsti – Greenwood 1979: 286.

Diagnosis

Astatoreochromis straeleni can be distinguished from A. alluaudi by the possession of 3-4 anal spines (usually 3) vs. 4-7 (usually 5-6); 16-18 [exceptionally 19 (f1)] dorsal spines vs. 17-19 dorsal spines [rarely 16 (f2) or 20 (f2)].

Etymology

Named in honour of Prof. V. Van Straelen, Director of the Musée du Congo Belge, Tervuren, Belgium from 1926 to 1954.

Type material

Holotype

IRSNB 75 , Rivière Lukuga, Région d’Albertiville, DRC.

Specimens examined

Astatoreochromis straeleni : DEMOCRATIC REPUBLIC OF CONGO: IRSNB 75, 78.9 mm SL, holotype, Lukuga River, Albertville region, coll. Dr Poyer (purchased); MRAC 107795, 81.2 mm SL, Lukuga, ‘près du lac d’Arbertville’, coll. Exploration hydrobiologique du lac Tanganyika, 30 Oct. 1946; MRAC 84.2.P.1-2, 51.2-54.0 mm SL, Kiliba River, coll. M. Baluku, 17 Nov. 1982. BURUNDI: MRAC 95.98.P.199, 81.4 mm SL, Kimirabasore, Kajeke swamps, coll. L. De Vos, 9 Feb. 1995; MRAC 73.68.P.165-170, 54.6-71.3 mm SL, small branch of the Rusizi River, near Lake Tanganyika, coll. Brichard, May 1973; MRAC 73.68.P.171, 82.9 mm SL, Rusizi swamps near Lake Tanganyika, coll. Brichard, 1973; MRAC 73.68.P.172-173, 50.3-65.7 mm SL, ‘Port de Bujumbura’, coll. Brichard, Feb. 1972; MRAC 91.62.P.1794, 79.9 mm SL, Gatumba swamps, 3°05’ S – 29°15’ E, coll. L. De Vos & P. Weiler, 13 Aug. 1991; MRAC 91.89.P.33, 96.4 mm SL, Gatumba swamps, 3°05’ S – 29°15’ E, coll. P. Weiler, 8 Sep. 1991 91.89.P.83-92, 66.1-103.5 mm SL, Gatumba swamps, 3°05’ S – 29°15’ E, coll. P. Weiler, 1-21 Sep. 1991; MRAC A9.13.P.75-105, 55.7-75.8 mm SL, Gatumba swamps, 03°20’18.6” S – 029°13’42.7’’ E, coll. Banyankimbona, 28 Jan.-11 Feb. 2009; MRAC B1.3.P.1-12, 55.5-88.4 mm SL, Gatumba swamps, 03°20’21.6’’ S – 029°13’56.9’’ E, coll. G. Banyankimbona, 07 Nov. 2010, MRAC B0.3.P.5-7, 57.2- 74.2 mm SL, Kideheri pool, Rusizi basin, Karwema village, 03°06’15.0’’ S – 029°15’27.8’’ E, coll. G. Banyankimbona, 6 Dec. 2009; MRAC B0. 3.P.8-10, 72.4-75.0 mm SL, Kinake pool, Rusizi basin, Nyamitanga village, 03°03’52.9’’ S – 029°15’40.2’’ E, coll. G. Banyankimbona, 9 Dec. 2009; MRAC B0.3.P.19-20, 61.7-65.6 mm SL, Kameme pool, Rukoko natural reserve, 03°11’59.4’’ S – 029°13’47.8’’ E, coll. G. Banyankimbona, 7 Dec. 2009.

Astatoreochromis vanderhorsti : BURUNDI: MRAC A9.13.P.55-74, 61.3-85.7 mm SL, Malagarazi River, Butezi village, 03°55’01,64’’ S – 030°15’22,3’’ E, coll. G. Banyankimbona, 13-15 Dec. 2008; MRAC B0.3.P.1, 59.0 mm SL, Malagarazi river, Mutwana village, 03°51’25.2’’ S – 030°17’53.5’’ E, coll. G. Banyankimbona, 31 Jul. 2009; MRAC B0.3.P.2, 72.2 mm SL, Malagarazi River, Butezi village, 03°55’01,64’’ S – 030°15’22,3’’ E, coll. G. Banyankimbona, 1-2 Aug. 2009; MRAC B0.3.P.3, 62.5 mm SL, Mazimero River, Nyamateke swamp, Gasunu village, 03°53’28.4’’ S – 030°13’03.7’’ E, coll. G. Banyankimbona, 5 Aug. 2009; MRAC 91.30.P.558, 76.5 mm SL, Butezi, fishermen’s village, Malagarazi River, 3°55’ S – 30°15’ E, coll. De Vos & Taverne, 4 Apr. 1991; MRAC 91.61.P.944, 81.7 mm SL, Butezi, fishermen’s village, Malagarazi River, 3°55’ S – 30°15’ E, coll. Taverne, Jun. 1991; MRAC 91.30.P.559, 43.7 mm SL, Nyamiviro rivulet, affl. Malagarazi, 6 km on road from Kinyinya to Makebuko, 3°37’ S – 30°20’ E, coll. L. De Vos & L. Taverne, 5 Apr.1991; MRAC 91.62.P. 1795-1796, 66.1-70.2.5 mm SL, Nyamiviro rivulet, affl. Malagarazi, 6 km on road from Kinyinya to Makebuko, 3°37’ S – 30°20’ E, coll. De Vos & Taverne, 6 Apr. 1991; MRAC 96.31.P.1425, 64.0 mm SL, Nyamiviro rivulet, affl. Malagarazi, 6 km on road from Kinyinya to Makebuko, 3°37’ S – 30°20’ E, coll. L. De Vos & L. Taverne, 3 Jun. 1992. TANZANIA: BMNH 1953.11.4, holotype, 111.3 mm SL, from Katare swamps, Malagarazi basin, coll. G.J. Lockley, 11 Apr. 1953; BMNH 1953.11.4 (18 specimens), paratypes, 59.2- 79.8 mm SL, same data as holotype.

Description

Based on the holotype and 85 specimens. Morphometrics and meristics are given in Table 5 . Small to medium sized species (max 111.3 mm SL) with moderately compressed body. Snout pointed or slightly concave. Eye diameter as long as, or shorter than, interorbital width. Caudal peduncle variable, ranging from somewhat longer than deep to just slightly deeper than long. Gill rakers on lower part of the anterior arch thick and stout, 8-10 [8 (f33), 9 (f41), 10 (f11)], last three or four reduced to small nubs. Upper and lower jaws with 1-3 inner rows of tricuspid teeth. Outer series in both jaws composed of unequally bicuspid and sometimes compressed teeth, only slightly cuspidate or conical in the posteriormost part of both jaws. Tooth number of outer rows increases with size: 32-56 in upper jaw and 23-44 in lower jaw. Flank scales around lateral line ctenoid, elsewhere cycloid; generally 29-32 longitudinal line scales, excluding the small scales on caudal fin base [28 (f3), 29 (f10), 30 (29), 31 (f26), 32 (f14), 33 (f2)]; cheek with 3 (f49) or 4 (f35) [rarely 5 (f1)] scale rows; scales between pectoral and pelvic fins 4(f51) or 5 (f30) [rarely 3 (f1) or 6 (f2)]. Dorsal fin spines 16-18 [exceptionally 19 (f1)], soft rays 8-10 [8 (f8), 9 (f52), 10 (26)]. Anal fin spines 3-4 (usually 3), rays 8 (f19), 9 (63) or 10 (f4). Pectoral fin rays 13 (f47) or 14 (f26) [rarely 11 (f1) or 12 (f2)]. Caudal fin rounded. LPJ triangular, longer than, or almost as long as, wide (LPJ width 83.3-102.8 % of LPJ length); its teeth in the lateral external rows slender and cuspidate, the central two to four rows with a mixture of molariform (anterior part of the dentigerous area) and enlarged but cuspidate teeth.

Colour pattern of live specimens

See Fig. 6 for general appearance. Dorsally and dorso-laterally dark grey-yellowish, orange yellowish on opercle, upper part of cheek, chest and belly. Lips and lower part of cheek iridescent blue. Fins orange yellowish, dorsal with red edge, more pronounced posteriorly. Anal fin with 3-5 horizontal rows of bright orange-yellow ocelli. Females with similar but smaller ocelli. Caudal fin with black dots arranged in 6-8 more or less regular vertical rows. While general appearance remains the same, live colour pattern appears influenced by characteristics of the water in which the individuals live. Rusizi specimens caught in water with a high conductivity (more than 250 µs/cm) and muddy blackish bottom substrate in the Gatumba swamps near Lake Tanganyika during the rainy season have a darker colour pattern ( Fig. 6B ). Specimens caught in the pools associated with the Rusizi River more to the north and in marginal vegetation of the Malagarazi River are generally lighter coloured ( Fig. 6A ).

Colour pattern of preserved specimens

General appearance dark brown for recently preserved specimens turning lighter grey or dark grey after a couple of years of preservation. Fins dark grey, edge of anal and anterior part of dorsal and pelvic fins dark brown to blackish. No mid-lateral band present.A large blackish blotch at upper posterior end of gill cover, may be vague in some specimens. A blackish vertical bar below, or behind, the eye in all recently preserved specimens; this bar may disappear in specimens kept for some time in alcohol. Blackish dots arranged in interrupted horizontal rows in posterior portion of soft dorsal fin and in interrupted vertical rows in caudal fin. Anal ocelli always present but less visible distally, where anal fin is dark brown to blackish.

Distribution

Known from the Rusizi, Lukuga and Malagarazi basins and from the Luiche, a small affluent of Lake Tanganyika just north of the Malagarazi River delta. The species apparently also enters the lake as it was collected by Brichard in 1973 from the harbour of Bujumbura; in addition, De Vos et al. (2001) mentioned its presence at the harbour of Ujiji near Kigoma in Tanzania. Its presence in other affluents of Lake Tanganyika needs to be confirmed.

Ecology

Astatoreochromis straeleni is primarily a riverine species ( Greenwood 1954; Poll 1956, 1974), prefering clear water (pers. obs. GB). In the Malagarazi basin, no specimen was found in the main channel. The most important catch was made during the rainy season when specimens were caught in swampy flooded areas. The species was also caught in marginal vegetation of the Mazimero River, a small affluent of Malagarazi, with a high water transparency. In the Rusizi basin, the species was mainly caught in the Gatumba swamps where it is more abundant than in the Malagarazi basin; here also it was found mainly in vegetated areas with clear water. It was also common in the small swampy pools associated with the Rusizi River. The species was never caught in nor reported by the local fishermen from the main course of the Rusizi River. Greenwood (1954) reported the species to feed mainly on snails, ostracods and insects in the Malagarazi basin. Examination of stomach and gut content of 12 recently collected specimens (January 2011) from the Rusizi found snails (entire and fragmented shells) together with adult insect fragments (wings) and other invertebrate remains in four specimens. Two specimens contained some adult insect remains and other invertebrate material, but no snails. The guts of three other specimens contained a large amount of debris, sand and small undigested plant fragments. Finally, three mouthbrooding females had empty guts.

Reproduction

The species is a mouth-brooder but nothing has been reported about its breeding period. Among the specimens captured in the Malagarazi in December 2008 and in the Rusizi in January 2011, females were found with ovarian eggs at different developmental stages in their gonads. Those caught in January appeared to be at a more advanced stage and almost mature for spawning (diameter: 1.9-2.6 mm). Conversely, amongst the specimens caught in the Rusizi basin in February 2009, no females with developed eggs in their gonads were found. So, most probably the species reproduces at the start of the short dry season from December to January. Whether this is the only reproductive season cannot be determined from our data.

Figures

Fig. 6. Adult ♂♂ of Astatoreochromis straeleni (Poll, 1944). A. MRAC A9-13-P-555, 70.6 mm SL, collected on 13 Dec. 2008 in the Malagarazi. B. MRAC B1-3-P-1, 88.3 mm SL, collected on 7 Jan. 2011 in the Rusizi. (Photographs by GB)