Ladigesia
Small size; relatively elongated; dorsal behind the middle of the body; ventrals in the middle, inserted in front of the dorsal-level; adipose fin present; anal short, modified in males; apparently no other sexual dimorphism; lateral fine incomplete; dorsal region entirely naked up to front of adipose, the naked area corresponding, on both sides, to 3 or more normal scales-series. Posterior fontanel broadly open, anterior fontane! short, reaching to the level of middle of pupil; mouth supero-terminal; premaxillary elongated,its distal end bifid, armed with 4 tri- to quincuspidate teeth, and 2 smaller tricuspidate ones in front, obliquely inserted above the lip, at least in adults (see figure below); maxillary without teeth, with a paddle-like free end, whose base is articulated with the above-mentioned premaxillary fork; mandible of adults armed with 4 bi- to quincuspidate teeth, the two mesial ones slightly pointing outwards, and with an externat tooth (on both sides) clearly pointing forward, inserted behind the lip (see figure below); the inner pair of small conical teeth, characteristic of Alestes, Micralestes, etc., is missing in adults.
Ladigesia roloffi: jaws of: aduit (female paratype), left side dissected, external view, semi-schematic assemblage.
In juvenile stage (about 20 mm), at least in aquarium-bred specimens, the teeth are narrower, tricuspidate at the most, with the outer premaxillary teeth less pointed forward, and no externat tooth on the mandible; instead, there is a regular outer series of 5 tricuspid teeth and a conical tooth behind. The peculiar dentary tooth-structure of the adult may be duc to the forward migration of the mesial outer tooth, whereas the conical inner one, also migrating forwards, would have taken its place (?).
Type species
Ladigesia roloffi Géry, 1968 by monotypy.
Currently, Ladigesia is monospecific.
Bibliography
Type and type locality
Ladigesia roloffi Géry, 1968: 78-87, fig. 1-7. Type locality: “Kasewe forest, Sierra Leone”. Holotype: ZMH 4270. Paratypes: ZMH 4271.
Common names
Danish: Roloffs tetra
English: Jelly bean tetra (USA), Sierra leone dwarf characin (USA, Global)
Finnish: Tulievätetra
German: Orangeroter Zwergsalmler/Sierra-Leone-Zwergsalmler
Description
Diagnosis: rather species, the dorsal fin always behind the middle of the body, the ventral fins approximately in the middle; the caudal peduncle quite narrow, owing to the shortness of the anal fin, its depth 1.35-1.8 in its length; pectorals i9ii, short, not reaching ventrals; ventrals i6i, short, not reaching anal; anal with a straight base and a concave border in females, iii13-14(i) rays; in males, the anal base is somewhat “wavy”, following the lowering of the anterior part of the anal keel, with ii14(i) (rarely 13) rays: the first, rudimentary, unbranched ray is apparently missing, like in certain other male alestids; dorsal ii7i (once 8i); caudal viii9/8 lvi; predorsal and preventral regions not angulated nor keeled, more or less rounded, the former one entirely naked from the post-occipital up to the dorsal, then almost up to the adipose behind, as well as, laterally, on almost a fourth of the surface of the sides; anal and caudal bases not covered with scales. Squamation (5-7) 34-35, 7 to 9 in a transverse oblique series above ventral (towards dorsal), 14 or 15 around peduncle; gill-rakers 7-9/11-12. Detailed proportions and counts in table below.
Ladigesia roloffi: morphometric and meristic data.
The characters of the head and of the dentition have been described in the generic diagnosis.
Maximal reported size: 31 mm SL (male).
Colour: the coloration of Ladigesia roloffi is most gorgeous: when alive, the mature wild fish bas its fins (including the middle part of the paired ones), the upper part of the eye and, in a somewhat less intense tone, the whole body, bright vermilion; the unbranched dorsal and caudal rays, as weil as the tip of their branched ones, are black.
After preservation, there exists a black longitudinal line on body, spreading outwards on peduncle, and continuing up to the tip of the median caudal rays: this line corresponds with a golden band visible in vivo. The anal base is marked, in females, by a band of chromatophores which, in males, attains the proportion of a real, apparent spot; there is no humeral spot.
Distribution
Kasewe in the Gbangbaia basin (small stream systems west of Jong) in Sierra Leone. Also appears to be present in Du River (see also Faunafri).
It is only known from one location, the type locality Kasewe (Sierra Leone) according to Paugy (2003) and possibly in a second locality in Liberia according to FishBase. The estimated extent of occurrence and area of occupancy are less than 5,000 km² and less than 500 km², respectively. The extent and quality of habitat is undergoing and continuous decline due to mining, urban and deforestation developments. The species is therefore assessed as Endangered.
Major threats: the extent and quality of habitat is undergoing a continuous decline due to mining, urban developments and deforestation.
Bibliography
