Garra sannarensis, Moritz & Straube & Neumann, 2019

Moritz, Timo, Straube, Nicolas & Neumann, Dirk, 2019, The Garra species (Cyprinidae) of the Main Nile basin with description of three new species, Cybium 43 (4), pp. 311-329 : 322-324

Garra sannarensis sp. nov.

( Figs 15-16 , Tabs IV-V)

Garra sp. “Sennar” Neumann et al., 2016

Material

Holotype. – ZSM 47246 (ex ZSM 35141 #1), 36.4 mm SL, Sudan: Blue Nile at outlet canal of Sennar dam (N13.55° E33.63°), coll. D. Neumann, M. Mohammed & N. Pöllath, 17 Jan. 2007.

Parayptes. – ZSM 35141 (3 now 1), 35.9, same data as holotype ; DMM IE/15075 (1) (ex ZSM 35141 ), 36.2 mm SL, same data as holotype ; ZSM 46922 (1), 21.1 mm SL, Sudan: Blue Nile on bedrocks below outlet canal of hydroelectric power unit of Sennar dam (N13.55° E33.63°), coll. D. Neumann, 26 Mar. 2018 .

Diagnosis

From all other African Garra species except of G. napata , G. sannarensis is distinguished by its intermediate developed sucking disc (type B) (vs. fully developed disc [type C] in G. blanfordii , G. chebera , G. congoensis , G. ethelwynnae , G. hindii , G. ingestii , G. makiensis , G. ornata , G. quadrimaculata , G. trewavasae , G. vinciguerrae and G. jamila ; and weakly developed disc [type A] in G. allostoma , G. dembecha , G. dembeensis , G. duobarbis , G. regressus and G. tana ) and the absence of predorsal scales (vs. presence of at least some predorsal scales in G. aethiopica , G. blanfordii , G. chebera , G. congoensis , G. dembecha , G. geba , G. hindii , G. ignestii , G. lancrenonensis , G. makiensis , G. ornata , G. quadrimaculata , G. regressus , G. tana , G. trewavasae , G. waterloti and G. vinciguerrae ).

Garra sannarensis is distinguished from all other species of the Main Nile basin by a caudally pointed lateroposterior flap of disc (vs. rounded or absent); furthermore from G. vinciguerrae by moderately sized rostral cap and densely papillated area towards mouth (vs. very prominent rostral cap with fringed but smooth posterior margin), lower-lip pad quadrangular (vs. round); from G. napata and G. jamila by dorsal parts of flanks continuously covered with scales (vs. naked dorsolateral flanks along anterior part dorsal fin base), and further from G. napata by its slender head and inconspicuous cheeks which are not or hardly visible when viewed from above (vs. broad head and visible cheeks when viewed from above). Garra sannarensis is distinguished from G. sp. “ White Nile ” by its very short barbels, which do not reach the pad when bent inwards (vs. barbels nearly touching each other when flexed midways).

Description

Based on holotype ( Fig. 15 ) and 4 paratypes. Holotype and 2 paratypes stranded and collected from the rocky but dry shore; fourth paratype is a juvenile ( Fig. 16 ). A probably small Garra with up to 36.4 mm SL (46.0 mm TL). Counts and proportional measurements are given in tables IV and V. Head and anterior body region dorsoventrally slightly flattened, gradually more compressed laterally towards tail. Cheeks not or hardly visible when viewed from above. Disc intermediate (type B), but with broad, papillate and triangular lateroposterior flap pointing caudally; central callus almost quadrangular ( Fig. 5C ). Rostral cap densely covered with papillae towards mouth opening, two pairs of very short stout maxillary barbels.

Dorsal fin originates midway on body, distal margin slightly convex; one minute unbranched ray perceptible only via X-ray imaging and deeply embedded into anterior dorsal fin tissue followed by one or two smaller and one large simple ray and 7 branched fin rays. Pectoral fins inserting low on body; pelvic fins exceed beyond vent without reaching anal-fin base. Anal fin with one or two smaller and one large simple ray and 5 branched rays. Caudal fin emarginated with probably rounded upper and lower lobe. Entire body densely covered with large scales, except chest, belly and postpelvic area; area in front of dorsal fin insertion scaleless ( Fig. 6D ).

Colouration. – Preserved specimens dark brown on flanks, dorsum and dorsal half of head; ventral third of flanks and lower half of head slightly lighter, distinct transition to pale whitish belly ( Fig. 15 ). Scale centres light, outer rims dark and pigmented, towards tail in posterior body half forming an irregular dark reticulate pattern, pigmentation along mid later stripe slightly darker. Vertically elongated humeral blotch exceeds beyond first lateral-line scale; caudal peduncle with dark vertical blotch and subsequent small dark stripe running through the last scale row on the base of the caudal fin rays; caudal rays conspicuously pigmented and dark, membranes in-between clear and hyaline. Dorsal membrane with four spots at base of branched fin rays 3 to 6 and with distinct dark band in the middle of the membrane (not as prominent as in G. napata ; Fig. 7D ).

Live coloration recorded only from a single juvenile ( Fig. 16 ): body cream-coloured, flanks with a more or less pronounced greenish band; scales on dorsal half of flank with dark outer rim causing a reticulate pattern behind the dorsal fin and on the tail; back along dorsal fin base, nape and head densely pigmented but not very dark. Head and body flanks with prominent greenish iridescent, being most intense on opercles. Red postopercular spot present, about half the size of the dark humeral blotch. Membrane of dorsal fin hyaline; faint dark markings and base of 3 rd to 5 th branched dorsal ray recognisable, mid-dorsal dark band still rudimentary and hardly visible. Pectoral, pelvic and anal fins hyaline, anterior margins of ventral fins and tip of dorsal fin with white margin; dark and vertically elongated blotch at end of caudal peduncle followed by a small dark stripe running through the posterior rim of last scale row on the caudal fin insertion, membranes between innermost caudal rays covered with melanophores and dark; caudal fin membrane hyaline, single melanophores along rays turn entire fin dusky; dorsal and ventral border of caudal fin slightly orange.

Distribution

So far recorded only from the swift rip-rap embankment at the outlet canal of the hydroelectric powerhouse of Sennar dam ( Fig. 1 ) and the immediately adjacent bedrocks where the canal joins the Blue Nile again, opposite of the left spur dyke of the main dam.

Figures

Figure 1. – Records of Garra species from the Main Nile basin (dotted line). Star – Garra vinciguerrae; diamond – G. napata; square – G. jamila; triangle – G. sannarensis; cross – G. sp. “White Nile”; numbers indicate the cataracts of the Nile river.

Figure 5. – Underside of head show- ing the different types of sucking-discs. A: Garra vinciguerrae; B: G. napa- ta; C: G. sannarensis; D: G. jamila, holotype; E: G. jamila, large speci- men; F: G. sp. “White Nile”. Scale bars = 5 mm.

Figure 6. – Scaled (dark) and unscaled (light grey) areas in dorsal view. A: Garra vinciguerrae; B: G. napata; C: G. jamila; D: G. sannarensis.

Figure 7. – Dorsal fin melanophore pattern. A: Garra vinciguerrae; B: G. napata; C: G. jamila; D: G. sannarensis.

Figure 15. – Garra sannarensis, ZSM 47246, 36.4 mm SL, outlet of Sennar dam, Blue Nile, Sudan, 17 Jan. 2007. Scale bar = 10 mm.

Figure 16. – Live specimens of Garra sannarensis sp. nov., 21.1 mm SL (ZSM 46922); Sennar, Blue Nile, Sudan, 26 Mar. 2018.