Astyanax nasutus Meek 1907
Creators: name: Schmitter-Soto, Juan J.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Characiformes
Characidae
Astyanax
Astyanax nasutus

description: Astyanax nasutus Meek 1907   
(Figure 28; see Rosen 1972, for illustration of holotype)  
 Astyanax aeneus non Günther, partim. Astorqui 1972.   
 Deuterodon nasutus (Meek 1907): Lucena and Lucena 2002:113 et seq.   
 Diagnosis   
 Diagnosed from other Astyanax species in Nicaragua and neighbouring Costa Rica as follows: supraoccipital in dorsal view, long, narrow-based (shorter, wide-based in A. cocibolca, A. nicaraguensis and A. orstedii); 2 dorsoposterior projections of metapterygoid (1 in A. cocibolca); gill rakers on first arch lower arm, mean 11 (14 or more in A. nicaraguensis, A. bransfordii and A. cocibolca); pelvic bone, proximal edge convex (straight in A. nicaraguensis); caudal vertebrae 20 (19 in A. bransfordii).   
 Redescription   
 A species of Astyanax, subgenus Astyanax (i.e. with a complete predorsal series of scales).   
Head profile straight; snout pointed to squarish; lower lip protruding; mouth terminal. Pectoral fins do not reach pelvic fin origin; anal and dorsal fins usually do not overlap. Lobes of caudal fin, subequal.  
D. 9–10; A. 25–28; pect. 11. Procurrent unsegmented dorsal rays on caudal fin, 9 or fewer. Gill rakers on first arch, 19–22; on lower limb, 11–13. Scales on lateral line, 35–37; predorsal scales, 11; scale rows from lateral line to base of first dorsal-fin ray, 7–8.5; to base of pelvic fin, 5.5; to base of pectoral fin, 4. Nuptial tubercles, not seen. Total vertebrae 32–33, 20 caudal. See also Rosen (1972).  
Largest examined specimen, 82.1 mm SL. Body depth 34–37% SL. Head short, 23–31% SL; orbital diameter, 29–30% HL (further morphometric data appear in Table 4; see also Meek 1907).  
Anterior fontanel long, straight-sided, sharp-tipped. Supraoccipital process in dorsal view, long, narrow-based, angled in lateral view. Vomer rostrally undulate. Highest tooth on dentary, fourth; posterior teeth, not abruptly smaller. Dorsal edge of longer articular arm, straight. Maxillary, with a convex, notched anteroinferior edge; 4–6 teeth. Quadrate, dorsal process not expanded. Metapterygoid, rostral arm longer than ventral, 2 dorsorostral projections. Urohyal rostral end turned up, blunt; its ventrorostral edge convex, its ventral apex about equidistant between rostral and caudal ends; ceratohyal foramen comet-shaped; rostral vertices of ceratohyal angled, the ventral side straight. Upper pharyngeal bones, S-shaped; lower pharyngeal plate single, its caudal side straight. Dorsal side of hyomandibular, convex. Opercular dorsal edge, concave-convex; sides of dorsal half, parallel; posterior edge, dorsally and ventrally straight; ventral tip, rounded. Interopercle, posterior edge, straight-convex, with a spine. Preopercular anterodorsal edge, with a median convexity; ventral rim, straight; posteroventral edge, curved; 2 parallel canals at angle. Five predorsal bony elements. Caudad process of postcleithrum, digitiform, concave-sided. Dorsal tip of scaphium, truncate; caudal tip, sharp; dorsoposterior edge, slightly concave. Neural spines under dorsal fin, straight. Postanal element, short. Seventh caudal vertebra from tail, with a haemal spine displaced caudad. Largest hypuric plate, rostral edge straight. Epuric plate on last neural spine, convex-sided.  
Humeral spot, squarish; caudal spot, on peduncle and on fin. Colour in life, typical: ‘light olivaceous, a broad plumbeous band from upper edge of opercle to base of caudal, broadening into a caudal blotch’ (Meek 1907, p. 108).  
 Type material and depositor   
Holotype FMNH 5909, 125 mm SL, Lake Managua at Managua City, Nicaragua, coll. S.E. Meek. Paratypes: FMNH 5908 (12 specimens), 5910; same collection data as holotype; CAS 3949 (2 specimens), Lake Managua at Cisplaya, same collector and date.  
 Distribution   
Endemic to Lake Managua and River San Juan, Nicaragua (Figure 28).  
 Remarks   
 Astyanax nasutus is Ornelas-García et al.’s (2008) clade VIII. Synonymised to A. aeneus s. l. by Astorqui (1972) only because of overlap in snout and maxillary length.
description: Published as part of Schmitter-Soto, Juan J., 2017, A revision of Astyanax (Characiformes: Characidae) in Central and North America, with the description of nine new species, pp. 1331-1424 in Journal of Natural History (J. Nat. Hist.) (J. Nat. Hist.) 51 (21 - 24) on pages 1392-1393, DOI: 10.1080/00222933.2017.1324050, http://zenodo.org/record/5181888