形态学资料 Fontitrygon garouaensis
检索表
Abnormalities
主要参考文献 Compagno, L.J.V. and T.R. Roberts, 1984
形态描述的性别
Bones in OsteoBase

性别内容

特殊器官 claspers (m)
不同的外表
不同的颜色
附注 Teeth of males with triangular, concave, cuspidate crowns; females with low, rhomboidal, truncated, cuspless crowns (Ref. 26277).

稚鱼与成鱼的特徵描述

显着的特徵
侧面体型 other
横切面 flattened
头部背面描绘
眼的类型
口/吻尖的类型 more or less normal
口的位置 sub-terminal/inferior
Type of scales placoid scales
鉴别

Diagnosis: A moderately large and thin-bodied freshwater dasyatid; disc flatter than in any other West African dasyatid, its depth only 8.7-11.0% of disc width vs. 11.0% or more in other species; denticles on dorsal surface of disc highly variable, sometimes absent, always restricted to central portion; pearl spine absent or represented by 2-3 low denticles (Ref. 26277). It is most similar to the small marine species Dasyatis margaritella and the larger marine species Dasyatis margarita, both of which have well-developed pearl spines and shorter snouts (Ref. 26277).

Description: Disc oval, strongly flattened and broadly rounded at corners; tip of snout projecting as a small triangular process beyond anterior disc margin (Ref. 31256, 81259, 81625). Mouth slightly arched; upper jaw with 5-7 and lower jaw with 7-9 functional tooth series; a total of 32-40/37-45 rows of jaw teeth; teeth in males with a central cusp, blunt in females; a transverse row of five elongated fleshy mouth papillae (Ref. 26277, 81259, 81625). Nasal curtain posteriorly fringed, eyes and spiracles adjacent (Ref. 81625). Pelvic fins mostly concealed by disc in dorsal view (Ref. 81625). Tail long and thin, whip-like, with a denticulate sting at base, a short dorsal ridge behind the sting, and a ventral fold; tail base oval in cross-section with greatest width at base not as great as interorbital distance; caudal sting markedly lender (Ref. 81259, 81625). Skin armour variable: disc smooth in juveniles, the dermal denticles appearing with growth; the granulation remains restricted to the central disc area, sometimes including a nacreous tubercle, and usually a longitudinal row of 2-4 rounded or heart-shaped tubercles (Ref. 81259).

Colouration: Back of disc and pelvic fins uniformly brownish- to greyish-beige or gray-brown above, without spots or prominent markings, although some specimens have diffuse dark marblings; white below and without dark margins; tail brownish, darker or blackish behind the sting, lighter below (Ref. 26277, 81259, 81625).

鉴定难易度

分节特性 Fontitrygon garouaensis

侧线 打断: No
侧联机的鳞片
侧联机鳞片数
侧生系列的鳞片
侧联机的鳞片列
侧线下的鳞片列
尾梗周围的鳞片
触须
鳃裂 (仅限于鲨鱼/ 鱼) 5present
鳃耙
在下肢上
上枝鳃耙
总数
脊椎骨
肛门前
总数 120 - 131

背鳍 (s)

属性
鳍数
离鳍号码 Dorsal   
Ventral  
棘总数
软条总数
脂鳍 absent

尾鳍

属性

臀鳍 (s)

鳍数
棘总数
软条总数

偶鳍

胸鳍 属性  transformed to 'aerofoils'
脊椎     
软条   
骨盘的 属性  more or less normal
位置    
脊椎     
软条   
主要参考文献 (例如 9948)
字汇 ( 例如 cephalopods )
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