Microgobius cumana, Schwarzhans & Aguilera, 2024

Microgobius cumana n. sp.

Figure 29a–g View Fig

Holotype NMB P15671 View Materials ( Fig. 29b View Fig ), Calabrian , Cumaná FM , Venezuela, PPP 3038 .

Paratypes 7 specimens same data as holotype ( NMB P15672-78 View Materials ) .

Referred specimen 43 specimens same data as holotype .

Etymology Named after the type formation, the Cumaná FM.

Diagnosis Otolith size up to 1.9 mm in length. OL:OH = 0.79–0.93. Otolith shape high-bodied; dorsal rim high, with angular, high predorsal angle, obtuse middorsal angle and short but angular to pointed postdorsal projection. Sulcus relatively short and narrow, with low ostial lobe and tapering caudal tip; OL:SuL= 1.7–1.8; sulcus inclination angle 13–17°. Subcaudal iugum long, narrow. Ventral furrow close to ventral rim of otolith, regularly curved.

Description Otolith size up to 1.9 mm in length (holotype 1.4 mm). OL:OH = 0.79–0.93, mostly 0.79–0.87, but largest specimen 0.93 ( Fig. 29a View Fig ); OH:OT = 3.4–4.0. Otolith shape high-bodied. Dorsal rim with high, angular to slightly rounded predorsal angle, obtuse middorsal angle and short but angular or pointed postdorsal projection. Anterior rim vertical, with broad, shallow concavity at level of ostium; posterior rim vertical to slightly inclined and broadly concave. Ventral rim flat to slightly curved, horizontal. Preventral angle orthogonal, postventral angle rounded. All rims smooth, except dorsal rim intensely lobed in largest specimen ( Fig. 29a View Fig ).

Inner face flat in vertical direction and slightly bent in horizontal direction. Sulcus moderately long and wide, with broad ostial lobe; cauda straight, with rounded tip, not particularly deepened; sulcus inclination angle 13–17°; OL:SuL= 1.7–1.8. Subcaudal iugum long, narrow, may expand over posterior tip of cauda in juvenile specimens ( Fig. 28h View Fig ). Dorsal depression moderate in size, with indistinct margins. Ventral furrow distinct, moderately close to ventral rim of otolith and regularly curved. Outer face with slight ventral umbo, smooth.

Discussion Microgobius cumana is recognized by the high-bodied otolith with its characteristic shape of the dorsal rim, the relatively short sulcus (OL:SuL = 1.7–1.8), the low ostial lobe and tapering caudal tip. In the latter two characters it resembles otoliths of M. microlepis with which it occurs parallel at the same location, but differs in the specific shape of the dorsal rim and the more compressed appearance (OL:OH = 0.79–0.87, rarely 0.93 vs 0.85–0.92) and the more steeply inclined sulcus (13–17° vs 9–11°). Microgobius cumana also resembles the otoliths of extant M. thalassinus ( Fig. 29h–i View Fig ) from the West Atlantic and M. brevispinis (according to drawings provided by D. Nolf) from the East Pacific, but differs in the specific shape of the dorsal rim and the broadly concave posterior rim (vs vertical).