Microgobius aphioides, Schwarzhans & Aguilera, 2024

Microgobius aphioides n. sp.

Figure 31a–e View Fig

Holotype NMB P15710 View Materials ( Fig. 31a View Fig ), Zanclean , Cubagua FM, Venezuela, PPP 2549 .

Paratypes 5 specimens Zanclean, Cubagua FM , Venezuela, 1 specimen PPP 2568 ( NMB P15711 View Materials ) , 2 specimens PPP 3057 ( NMB P15712-13 View Materials ) , 1 specimen PPP 3066 ( NMB P15714 View Materials ) , 1 specimen PPP 2549 ( NMB P15715 View Materials ) .

Referred specimen 71 specimens Zanclean: 54 specimens Cubagua FM , Venezuela, 5 specimens PPP 2549 , 1 specimen PPP 2556 , 6 specimens PPP 2557 , 8 specimens PPP 3055 , 7 specimens PPP 3057 , 16 specimens PPP 2568 , 4 specimens PPP 2570 , 7 specimens PPP 2571 ; 7 specimens Cayo Agua FM , Atlantic Panama, PPP 1188 ; 9 specimens Springvale FM , Trinidad, KR-1216 ; 1 specimen La Vela FM , Venezuela, PPP 2532 .

Etymology Named after the resemblance to otoliths of the northeastern Atlantic and Mediterranean genus Aphia .

Diagnosis Otolith size up to 1.25 mm in length. OL:OH = 0.8–0.85. Otolith shape high-bodied; dorsal rim elevated; predorsal angle and postdorsal projection rounded, not protruding. Preventral angle orthogonal, postventral angle rounded. Sulcus short, narrow, with broad, rounded ostial lobe and cauda posteriorly reduced by ingressing subcaudal iugum; OL:SuL = 1.7–2.0; sulcus inclination angle 13–18°. Subcaudal iugum long, wide, turning around caudal tip. Ventral furrow moderately close to ventral rim of otolith, regularly curved.

Description Otolith size up to 1.25 mm in length (holotype 1.0 mm). OH:OT = 3.2–3.5. Otolith shape high-bodied. Dorsal rim high, often with obtuse, rounded middorsal angle; predorsal angle high, broadly rounded, not protruding, postdorsal projection rounded or blunt, not protruding. Anterior and posterior rims near vertical and relatively straight. Ventral rim flat to slightly curved, horizontal. Preventral angle orthogonal, postventral angle rounded. All rims smooth.

Inner face completely flat. Sulcus small, short, narrow, with broad, rounded to triangular ostial lobe; cauda straight, short, with rounded or tapering tip; sulcus inclination angle 13–18°; OL:SuL = 1.7–2.0. Subcaudal iugum long, wide, turning upward posteriorly and then ingressing into posterior tip of cauda to various extends. Dorsal depression indistinct. Ventral furrow distinct, moderately close to ventral rim of otolith and regularly curved. Outer face evenly convex, smooth.

Discussion Te otoliths of Microgobius aphioides are smaller than most Microgobius otoliths and could be confused with otoliths of juveniles of other species. Te characteristic ingression of the subcaudal iugum into the rear part of the cauda is rarely observed in otoliths of juveniles of other species, but the shape of the sulcus with its low, rounded to triangular ostial lobe and the relatively wide subcaudal iugum distinguish M. aphioides from such otoliths of juveniles. Te smooth otolith rims and nearly vertical anterior and posterior rims distinguish M. aphioides from other species in the Microgobius camur plexus. Te ingression of the subcaudal iugum into the rear part of the cauda is stronger in M. aphioides than in M. glaber , resulting in a shorter sulcus (OL:SuL = 1.7–2.0 vs 1.5–1.6). Microgobius aphioides differs from M. camur in the relatively narrow ostium and the smooth otolith rims. Most similar morphologically are the otoliths of the small species M. praeglaber , which, however, is distinguished by its eccentrically forward-positioned sulcus and the curved ventral rim.