形態學資料 Fontitrygon garouaensis
檢索表
Abnormalities
主要參考文獻 Compagno, L.J.V. and T.R. Roberts, 1984
形態描述的性別
Bones in OsteoBase

性別內容

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

稚魚與成魚的特徵描述

顯著的特徵
側面體型 other
橫切面 flattened
頭部背面描繪
眼的類型
口/吻尖的類型 more or less normal
口的位置 sub-terminal/inferior
Type of scales placoid scales
鑑別

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).

鑑定難易度

分節特性 Fontitrygon garouaensis

側線 打斷: No
側線上的鱗片
側線上鱗片數
側生系列的鱗片
側線上的鱗片列
側線下的鱗片列
尾梗周圍的鱗片
觸鬚
鰓裂 (僅限於鯊魚/ 魟魚) 5present
鰓耙
在下肢上
上枝鰓耙
總數
脊椎骨
肛門前
總數 120 - 131

背鰭 (s)

屬性
鰭數
離鰭號碼 Dorsal   
Ventral  
棘總數
軟條總數
脂鰭 absent

尾鰭

屬性

臀鰭 (s)

鰭數
棘總數
軟條總數

偶鰭

胸鰭 屬性  transformed to 'aerofoils'
脊椎     
軟條   
骨盤的 屬性  more or less normal
位置    
脊椎     
軟條   
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