Microgobius robertsoni, Schwarzhans & Aguilera, 2024

Microgobius robertsoni n. sp.

Figure 30a–g View Fig

2014 Gobiidae , Genera and species indet. 2—Aguilera et al.: Fig. 12 View Fig /8–12/9.

Holotype NMB P15687 View Materials ( Fig. 30b View Fig ), Burdigalian , Cantaure FM, Venezuela, PPP 2539 .

Paratypes 12 specimens: 8 specimens Burdigalian , Cantaure FM , Venezuela: 5 specimens same data as holotype ( NMB P15688-92 View Materials ) , 3 specimens PPP 2545 ( NMB P15693- 95 View Materials ) . 3 specimens Burdigalian , Balboa FM , Dominican Republic, NMB 17290 View Materials ( NMB P400 View Materials ) . 1 specimen Aquitanian to Burdigalian, Pirabas FM , Brazil (MPEG- 1946- V) .

Referred specimen 238 specimens: 233 specimens Burdigalian, Cantaure FM , Venezuela: 87 specimens same data as holotype , 4 specimens PPP 2543 , 135 specimens PPP 2545 , 10 specimens PPP 2546 . 1 specimen Burdigalian, Brasso FM , Trinidad KR 6666. 1 specimen Aquitanian to Burdigalian, Pirabas FM , Brazil.

Etymology Named in honor of Ross Robertson (Panama City, Republic of Panama) for his contribution to the knowledge of the fishes of the tropical East Pacific.

Diagnosis Otolith size up to 1.8 mm in length. OL:OH = 0.83–0.88. Otolith shape high-bodied; dorsal rim high, relatively smooth, with rounded, obtuse postdorsal angle and short rounded postdorsal projection. Anterior rim ventrally expanded below ostium. Sulcus moderately large and wide, with broad ostial lobe and rounded caudal tip; OL:SuL = 1.4–1.5; sulcus inclination angle 15–22°. Subcaudal iugum moderately long, narrow. Ventral furrow close to ventral rim of otolith, regularly curved.

Description Otolith size up to 1.8 mm in length (holotype). OH:OT = 3.6–3.9. Otolith shape high-bodied. Dorsal rim high, regularly curved, with broadly rounded predorsal angle and broadly rounded middorsal angle, and short broadly rounded postdorsal projection. Anterior rim slightly inclined towards dorsal, with bulge or rounded projection ventral of ostial tip in specimens larger than 1.5 mm in length ( Fig. 30a, b, g View Fig ); posterior rim vertical to slightly inclined and with indistinct central concavity. Ventral rim flat to slightly curved, horizontal. Preventral angle recessed below bulge of anterior rim, postventral angle rounded. All rims smooth to slightly undulating.

Inner face nearly flat in vertical direction and slightly bent in horizontal direction. Sulcus moderately large and wide, with broad ostial lobe; cauda straight, with rounded tip, slightly deepened; sulcus inclination angle 15–22°; OL:SuL = 1.4–1.5. Subcaudal iugum moderately long, narrow. Dorsal depression small, with indistinct margins. Ventral furrow distinct, close ventral rim of otolith and regularly curved. Outer face nearly flat or with slight ventral umbo, smooth.

Discussion Microgobius robertsoni is characterized by the rather smooth otolith rims and, in larger otoliths longer than 1.5 mm, the bulge at the anterior rim below the ostium. Tese are also the characters distinguishing M. robertsoni from M. ecuadorensis . Microgobius robertsoni differs from the parallel occurring M. cantaurensis in the more compressed shape (OL:OH = 0.83–0.88 vs 0.95– 0.97) and steeper inclined sulcus (15–22° vs 12–15°), and from M. verecundus in the larger sulcus (OL:SuL 1.4–1.5 vs 1.55–1.75).