Microgobius chocorum, Schwarzhans & Aguilera, 2024

Microgobius chocorum n. sp.

Figure 28e–h View Fig

Holotype NMB P15661 View Materials ( Fig. 28e View Fig ), Tortonian, Tuira FM, Pacific Panama, Darien, PPP 1163 .

Paratypes 6 specimens Tortonian : 5 specimens Pacific Panama, Darien : 4 specimens Tuira FM , 2 specimens PPP 1593 ( NMB P15662-63 View Materials ) , 1 specimen PPP 1154 ( NMB P 15664 View Materials ) , 1 specimen PPP 1137 ( NMB P15666 View Materials ) ; 1 specimen Yaviza FM, PPP 1565 ( NMB P15667 View Materials ) ; 1 specimen Manzanilla FM , San José Member, Trinidad, PPP 2674 ( NMB P15665 View Materials ) .

Referred specimen 10 specimens Tortonian : 7 specimens Tuira FM , Pacific Panama, Darien , 1 specimen PPP 1137 , 6 specimens PPP 1163 ; 3 specimens Gatun FM , Atlantic Panama, PPP 2165 .

Etymology Named after the Chocó Indians living in the Chocó Province in Darien, Panama.

Diagnosis Otolith size up to 1.4 mm in length. OL:OH = 0.75–0.8. Otolith shape high-bodied; dorsal rim high, with weak postdorsal projection. Sulcus moderately long and wide, with relatively broad ostial lobe; OL:SuL = 1.45–1.65; sulcus inclination angle 16–18°. Subcaudal iugum long, narrow. Ventral furrow moderately close to ventral rim of otolith, regularly curved.

Description Otolith size up to 1.4 mm in length (holotype 1.35 mm). OH:OT = 3.5–4.3. Otolith shape high-bodied, with high dorsal rim and prominent middorsal angle. Predorsal angle rounded; postdorsal region rounded, not projecting. Anterior and posterior rims near vertical; posterior rim with weak central concavity. Ventral rim slightly curved, horizontal. Preventral and postventral angles rounded. All rims smooth, dorsal rims sometimes undulating or crenulated ( Fig. 28f 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 16–18°; OL:SuL = 1.45–1.65. 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 chocorum resembles the extant M. carri and M. crocatus . It differs from M. carri in the more high-bodied shape (OL:OH = 0.75–0.8 vs 0.85– 0.87) and from M. crocatus in the distinct middorsal angle (vs regularly curved) and in being more compressed (OL:OH = 0.75–0.8 vs 0.83–0.88). Otoliths of the extant M. meeki ( Fig. 28i View Fig ) and M. signatus ( Fig. 28d View Fig ) are similarly compressed, as far as can be judged from the available, somewhat formalin-eroded specimens. Otoliths of M. meeki differ from M. chocorum in the high postdorsal angle and the steeply inclined sulcus (25° vs 16–18°) and those of M. signatus in the small sulcus

(OL:SuL = 1.8 vs 1.45–1.65) and the low sulcus inclination angle (about 10° vs 16–18°).