Andersonia leptura Boulenger, 1900

Ferraris, Carl J. & Vari, Richard P., 2012, Review of the African catfish genus Andersonia (Teleostei: Siluriformes), Zootaxa 3210, pp. 39-49 : 42-47

Andersonia leptura Boulenger, 1900

Figure 1 ; Tables 1 & 2

Andersonia leptura Boulenger, 1900: 529 [Type locality: a pond near Koshek, Soudan (= Sudan). Holotype: BMNH 1907.12.2.2545].— Boulenger, 1905: 50 [listing].— Werner, 1906b: 1139 [redescription].— Boulenger, 1907: 392, pl. 76, fig. 4 [based on Boulenger, 1900; oversight of inner mandibular barbel in original description corrected; comparison of holotype with that of Slatinia mongallensis ; illustration of type].— Boulenger, 1911: 510, fig. 381 [based on Boulenger, 1910].— Pekkola, 1919: 118 [upper White Nile; noted as “not uncommon”].— Pellegrin, 1935: 136 [Omo River basin].— Pellegrin, 1936: 416 [occurrence in Lake Rodolphe =Turkana].— Worthington and Ricardo, 1936: 363 [in Lake Rudolf or Delta of Omo River, not collected and record based on literature].— Copley, 1941: 13 [ Kenya, Lake Rudolf = Turkana].— Sandon, 1950: 48, fig. 5 [Nile River].— Harry, 1953: 195 [listing].— Poll, 1957: 125, figs. 251–253 [listing, illustration; Nile basin].— Copley, 1958: 106, (fig. 62) [upper Nile and Lake Rudolf (=Turkana); drawing poor representation of species].— Daget, 1959: 679, fig. 4 [Débo Lake, Upper Niger River basin].— Blache, 1964: 208, fig. 117 [redescription; Chad basin].— Mathiasson, 1964: 116 –185 [White Nile].— Miton, 1965: 84 [ Chad basin].— Daget and Iltis, 1965: 162 [distribution].— Monod, 1968: 422, fig. 500 [osteology].— Roberts, 1975: 296 [listing, Omo River basin].— Daget and Durand, 1981: 739, pl. 18, fig. 68 [listing, Nile and Chad basins].— Abu Gideiri, 1984: 86, fig. 55 [brief redescription and illustration, Nile basin, Sudan].— Skelton and Teugels, 1986: 60 [listing].— Burgess, 1989: 114 [listing].— Lévêque et al., 1991: 136 [upper Niger River, Chad basin, Nile River, Turkana basin].— Skelton, 1992: 466, fig. 26.15 [West Africa, Tchad basin and lac Débo in central delta of Niger River].— Bailey, 1994: 956, fig. 6.1 [ Sudan, Nile River].— Poll and Gosse, 1995: 189, fig. 342 [listing, illustration].— He et al., 1999:117 –146 [anatomical comparison and phylogenetic placement].— Golubtsov et al., 2002: 167 [ Ethiopia, White Nile].— Golubtsov and Dzerzhinskii, 2003: 161, fig. 1a [redescription, White Nile].— Diogo, 2003: 432 [listing].— Golubtsov et al., 2004: 146 [dentition].— Moritz et al., 2006: 99, 105, fig. 8a [ Benin, Niger River, Malanville].— Ferraris, 2007: 24 [listing].— Seegers, 2008: 145, fig. [brief description].

Slatinia mongallensis Werner, 1906a: 327 [Type locality: Bahar-el-Gebel, bei Mongalla. Syntypes (3): NMW 79741 (1), ZMH 12016 (1), whereabouts of third specimen unknown; description appears to be based on single specimen].— Werner, 1906b: 1139, pl. 1, figs. 2–4 [more extensive description, assignment of name to synonymy of A. leptura ].— Skelton and Teugels, 1986: 60 [listing, as synonym of A. leptura ].— Ferraris, 2007: 24 [listing, as synonym of A. leptura ].

Andersonia pellegrini Boulenger, 1918: 427 [Type locality: Shari River, Ubanghi-Shari Colony, French Equatorial Africa. Holotype: BMNH 1918.11.12.13].— Pellegrin, 1919: 664 [listing, Chad basin].— Pellegrin, 1921: 48 [listing, Chad basin].— Holly, 1930: 249 [listed for Kameruns = Cameroon, without documentation of basis for citation].— Harry, 1953: 195 [first reviser, selecting A. pellegrini as valid over A. brevior ].— Poll, 1957: 125 [ Chad basin].— Kähsbauer, 1962: 162 [listing, Chad Basin].— Blache, 1964: 208, fig. 117 [synonymy with A. leptura ].— Daget and Iltes, 1965: 162 [as possible synonym of A. leptura ].— Skelton and Teugels, 1986: 60 [listing, as synonym of A. leptura ].— Ferraris, 2007: 24 [listing, as synonym of A. leptura ].

Andersonia brevior Boulenger, 1918: 426 [Type locality: Shari River, Ubanghi-Shari Colony, French Equatorial Africa. Holotype: BMNH 1918.11.12.13].— Harry, 1953: 195 [first reviser, selecting A. pellegrini as valid over A. brevior ].— Skelton and Teugels, 1986: 60 [listing, as synonym of A. leptura ].— Ferraris, 2007: 24 [listing, as synonym of A. leptura ].

Diagnosis. The same as the genus.

Description. Body elongate and progressively tapering vertically and transversely posteriorly. Greatest body depth located slightly anterior of dorsal-fin origin and greatest width at anterior limit of pectoral-fin insertion. Abdominal region transversely flattened. Dorsal and ventral profiles of body progressively converge from anal-fin origin to caudal-fin base. Caudal peduncle elongate, slender, and depressed over its length, but nearly as wide as high at caudal-fin base. Lateral line runs along midlateral surface of body and onto caudal-fin base. Surface of body penetrated by bony extensions of dorsolateral and ventrolateral processes extending from vertebral centra of abdomen and caudal peduncle. Exposed tips of dorsolateral vertebral processes visible from base of dorsal-fin origin to caudal-fin base. Processes on ventrolateral surface of body extend from slightly posterior of pelvic-fin origin to caudal-fin base. Exposed processes along abdomen appear as overlapping scutes, forming longitudinal ridges that do not meet along either dorsal or ventral midlines. Dorsolateral and ventrolateral processes on caudal peduncle form plates that extend to dorsal and ventral midlines, respectively, thereby encasing peduncle in bony cover. Total number of dorsolateral plates: 23 (5), 24 (22), 25 (7) or 26 (2). Total number of ventrolateral plates: 22 (4), 23 (17), 24 (13), or 25 (2). Anus and urogenital pore located immediately posterior of pelvic-fin base. Urogenital pore conical, of variable length. Vertebrae: 34 (3), 35 (33), or 36 (1). Ribs: 4 (35), or 5 (2).

Head broad from dorsal view with lateral margin slightly convex and narrowing anteriorly. Snout tip convex. Head broadly convex dorsally and nearly flat ventrally from lateral view. Snout long, approximately one-half head length and somewhat larger than interorbital width. Anterior margin of snout broadly rounded. Eye located entirely within posterior one-half of head. Anterior naris with short, rounded tube bearing high flap along posterior margin. Posterior naris ovoid, somewhat larger than anterior naris, and with low flap along anterior margin. Distance from posterior naris to anterior margin of eye less than distance between anterior naris and tip of snout. Posterior naris approximately equidistant between anterior naris and eye. Distance between anterior nares of each side equal to distance between anterior naris and tip of snout. Mouth ventral, moderately wide; width approximately one-third of head width. Lips smooth. Barbels moderately long, tuberculate along ventral margin and tapered distally. Maxillary barbel longest, reaching approximately to vertical through pectoral-fin origin. Inner mandibular barbel with base situated slightly lateral of midline; barbel extending posteriorly to margin of branchiostegal membrane. Outer mandibular barbel arises from angle of mouth and extends slightly beyond tip of inner mandibular barbel. Branchiostegal membrane continuous across midline with posterior limit of ventral portion of margin distinctly V-shaped. Gill slit extends posterodorsally to above pectoral-fin origin to horizontal through ventral margin of orbit. Humeral process acutely triangular with posterior tip rounded or pointed. Process very slender in smaller specimens. Epiotic process slender, extending parallel to supraoccipital spine, but only slightly more than one-half length of that process. Supraoccipital process moderately wide at base and tapering slightly posteriorly. Process with fine crest dorsally and separated posteriorly from small, trilobed nuchal shield by short gap.

Dorsal fin located anteriorly on body; fin origin at vertical through tip of adpressed pectoral fin and slightly anterior of vertical through pelvic–fin origin. Dorsal-fin margin convex, with first two branched rays longest. Dorsal-fin spinelet absent. First dorsal-fin ray segmented, unbranched; basal half of ray rigid, but ray flexible distally. Last dorsal-fin ray usually unbranched and without posterior membranous connection to body. Dorsal-fin rays: I,5 (1), I,5,i (23), I,6 (9), or I,6,i (1).

Adipose fin adnate and broadly triangular with slightly convex posterior margin. Fin origin situated above posterior portion of anal-fin base. Fin preceded by short spinous projection that extends approximately to middle of anterior margin of fin.

Caudal fin shallowly forked with rounded tips; fin symmetrical. Middle rays approximately three-fourths length of longest rays. Procurrent rays short, few in number and not extending far anteriorly on peduncle. Principal caudal-fin rays: i,5,5,i (2), i,5,6,i (6), i,6,5,i (10) or i,6,6,i (17).

Anal fin moderately large, quadrangular. Fin base entirely located in posterior half of body; fin origin at approximately middle of total length. First branched ray longest, rays decreasing gradually in length posteriorly; distal margin of fin nearly straight. Last anal-ray with little, or no, posterior membranous extension. Adpressed fin reaching approximately to vertical through posterior terminus of adipose-fin base. Anal-fin rays: ii,6 (2), ii,6,i (11), ii,7 (11), ii,7,i (4), ii,8 (5) or ii,8,i (2).

Pelvic fin smaller than pectoral fin; fin margin convex, with first branched ray longest. Posterior ray without membranous extension posteriorly. Pelvic fin insertion located ventral to anterior half of dorsal-fin base. Pelvic-fin rays: i,4,i (35).

Pectoral fin moderate; tip of adpressed fin extends to vertical through dorsal-fin origin but falls short of pelvicfin origin. Fin margin convex, first branched ray longest. Anterior ray stiff, not segmented and forming rigid nonserrate spine in largest specimens. Pectoral-fin rays: I,5,i (28) or I,6,i (7).

Coloration in alcohol. Body-pigmentation intensity highly variable across examined specimens, perhaps reflecting time in preservative and/or water conditions at collection localities. Pigmentation darker dorsally with dark brown coloration extending to ventral of lateral line on abdomen and caudal peduncle. Boundary between dark and paler pigmented regions generally distinct and straight, especially in specimens with well-developed darker coloration. Dark pigmentation over body interrupted by three distinct, pale saddles. First saddle extends from posterior half of dorsal-fin base ventrally beyond lateral line; second saddle extends dorsally from anterior to middle portions of anal-fin base, but not reaching adipose-fin origin; third saddle extends ventrally from posterior half of adipose-fin base to lateral line. Pale ovoid spot extends across dorsolateral region between head and dorsalfin origin; spot usually, but not always, confined to region dorsal of lateral line. Ventral and ventrolateral parts of abdomen with few scattered dark chromatophores, with distinct concentrations of pigment extending across pelvicfin base and anal-fin origin. Head dark dorsally and dorsolaterally, with irregular lighter patches at nares, along snout margin, ventral to anterior part of orbit, on opercle, and along dorsal midline between orbits. Ventral part of head with scattered chromatophores most concentrated anteriorly, especially along margin of lower lip. Barbels pale ventrally and with some dark pigmentation dorsally at bases; dark pigmentation extends nearly to tip of maxillary barbel.

Dorsal fin hyaline, with basal and subdistal bands of dark pigmentation, as well as scattered chromatophores between bands. Subdistal band broad anteriorly, tapering gradually posteriorly. Distal margin of fin pale. Adipose fin darkly pigmented anteriorly and distally, pale posteroventrally, with distinct demarcation between dark and pale areas. Caudal fin with dark basal spot extending distally onto each lobe. Caudal-fin lobes with subdistal ovoid dark spot; spots in darkly pigmented individuals blend with each other and/or with extensions of basal spot. Anal fin pale, with subdistal band of variable width and some dark pigmentation on fin origin. Pelvic fin pale, with broad subdistal band that covers all, or all but last, rays; fin with basal spot on dorsal surface of fin base and bases of first two branched rays. Pectoral fin pale, with broad irregular basal blotch of dark pigment on dorsal surface of fin base and, in darkly pigmented specimens, onto bases of middle rays; fin with broad subdistal band extending across dorsal surface of membranes; band decreasing in width posteriorly.

Coloration in life. A live specimen of Andersonia leptura was illustrated in Moritz et al. (2006, fig. 8a) in which the coloration pattern is much as in preservative other than for a reddish abdomen and a whitish coloration on the remaining portions of the body lacking dark pigmentation.

Distribution. Andersonia leptura has been found in the upper Niger and upper Nile river systems, tributaries of the endorheic Lake Chad basin as well as the Omo River, the principal tributary of the endorheic Lake Turkana (formerly Lake Rudolf) basin. Much of the distribution of Andersonia leptura fits the Nilo-Sudan Bioregion defined by Thieme et al. (2005) and is shared with various other groups of fishes. The presence of the species in the Omo River system presumably predates the isolation of Lake Turkana from the Nile system to the north approximately 7500 years BP ( Beadle, 1981: 179).

Habitat. Found in standing water, along the margin of a lake, on a muddy substratum ( Daget, 1959: 680). Remarks. Harry (1953) appears to be the first to have noted the two alternate names proposed in Boulenger (1918) for the species and, therein, he treated A. pellegrini as valid.

Golubtsov and Dzerzhinskii (2003) reported on a large series of specimens from the Alvero River [sic, for Alwero River], of the White Nile basin in southwestern Ethiopia that we were unable to examine. Not unexpectedly, those samples revealed greater variation in some meristics than had been reported previously, but agreed with our own data based on geographically more extensive samples ( Table 1 ). They reported statistically significant allometry in several characters notwithstanding the relatively small range of 22–37 mm SL among examined specimens, including negative allometric growth in the length of the head, paired fins, caudal fin, and distance from the snout to the pectoral-fin origin, and positive allometry in the distance from the tip of the snout to the anal-fin origin.

The presence of Andersonia leptura in the Omo River basin is based on a single collection of two specimens first reported by Pellegrin (1935: 136). We examined one of those specimens, which was delicate and did not radiograph well enough to obtain any meristic data. The specimen was otherwise comparable in overall body proportions to the samples from other basins, and we consider the Omo River population as conspecific with A. leptura .

Material examined. Chad Basin: BMNH 1918.12.11.13 (1, 38 mm, holotype of Andersonia pellegrini ), Chad, Shari River. MNHN 1958-0135 (4, 25–29 mm), Chad, Lake Chad. CAS 74839 (7, 30–34 mm), Central African Republic, Chad River basin, Gounda [Gounda River], near border with Chad (9°18' N, 21°12’ E). ZSM 26910 (5, 28–35 mm) Central African Republic, Chad River basin, Gounda [Gounda River] (9°18' N, 21°12’ E). CU 91440 (8, 29–35 mm), Central African Republic, Nana-Grébiz, Gribingui-Chari Drainage, Gribingui River at Kunga Bandoro. CU 91441 (5, 30–38 mm), Central African Republic, Nana-Grébiz, Gribingui-Chari Drainage, Gribingui River at bridge in Kunga Bandoro.

Nile River basin: BMNH 1907.12.2.2454 (1, 46 mm, holotype of Andersonia leptura ), Sudan, Nile River south of Wadi Halfa. ZMH 12016 (1, 26 mm, syntype of Slatinia mongalensis ) and NMW 79741 (1, 30 mm, syntype of Slatinia mongalensis ), South Sudan, Bar el Gebel, near Mongalla. NRM 16402 (1, 24 mm), South Sudan, White Nile, Tonga. ZSM 39755 (3, 29–33 mm), ZSM 39756 (3, 32–40 mm), ZSM 39757 (4, 28–38 mm), ZSM 39758 (3, 29–38 mm); South Sudan, Nile River at Taraq Island.

Niger River basin: BMNH 2006.4.18.37 (1, 33 mm), Benin, Moshe River. MNHN 1961-0600 (4 [of 10], 24– 26 mm), Mali, Niger River basin, Lidebo.

Omo River basin: MNHN 1933-0110 (1 [of 2], 24 mm), Ethiopia, Lake Turkana.

Figures

FIGURE 1. Andersonia leptura, CU 91440, 35 mm SL, Central African Republic, Nana-Grébiz, Gribingui-Chari Drainage, Gribingui River at Kunga Bandoro.

Tables

TABLE 2. Proportional measurements, expressed as a percentage, of Andersonia leptura. Mean and Ranges based on the holotype and 22 additional specimens.

Standard length (mm) Predorsal length/SL Head length/SL	Holotype 45.7 30.0 15.8	Mean 30.2 16.1	Range 29.3–45.7 27.9–33.1 14.9–16.8
Body depth at dorsal-fin origin/SL Body width at dorsal-fin origin/SL	9.0 -----	9.5 9.8	8.8–10.2 8.7–11.2
Caudal-peduncle length/SL Caudal-peduncle depth/SL Anal-fin base length/SL Dorsal-fin length/SL Pectoral-fin length/SL Pelvic-fin length/SL	29.5 1.2 13.1 ----- 14.1 12.3	30.9 1.3 12.5 16.5 14.8 12.9	28.9–33.2 1.1–1.5 11.0–13.2 15.8–17.9 13.7–15.4 12.3–14.6
Posterior limit of insertion pelvic-fin base to anus/SL Head depth/HL Head width/HL Snout length/HL	3.0 60.0 79.3 47.6	3.0 61.2 83.2 50.2	2.5–3.4 58.6–65.0 78.1–93.2 47.4–53.3
Orbit diameter/HL Interorbital width/HL	16.3 34.9	18.6 37.8	15.4–20.8 34.9–38.1
Postorbital length/HL Postorbital Length/ Snout Length Caudal-Peduncle Length/ Caudal-Peduncle Depth Body Width/Body Depth	33.5 70.5 244 -----	36.3 74.6 243 105	33.0–40.0 70.0–82.9 200–270 96–111