Urophycis regia (Walbaum, 1792)

Marancik, Katrin E., Richardson, David E. & Konieczna, Małgorzata, 2020, Updated Morphological Descriptions of the Larval Stage of Urophycis (Family: Phycidae) from the Northeast United States Continental Shelf, Copeia 108 (1), pp. 83-90 : 85-86

Urophycis regia

Figures 2B , 3B , 4

Genetic confirmation.— n ¼ 53; 1.7–26.5 mm SL.

Formalin-fixed larvae examined.— n ¼ 3,252; 1.1–7 mm SL.

Identification.— Very recently hatched U. regia were illustrated by Barans and Barans (1972) and Serebryakov (1978) from lab-reared eggs and larvae collected from strip-spawned adults. These smallest and least-developed larvae appear very similar to the recently hatched U. chuss , with possible differences in head pigment. Specimens at this stage were not included in our analyses and are not described here, but this stage included larvae 1–1.4 mm NL in our preserved samples.

The traits described in this study were visible in larvae as small as 1.1 mm NL and common on larvae by 1.5 mm NL. The lower jaw is more heavily pigmented than U. chuss with 2–4 melanophores that are often elongate and present on either side of the jaw. Occasionally, forebrain pigment was present externally in smaller larvae, but was generally absent until later in the postflexion stage. The pelvic fins develop at approximately 3–3.5 mm, later than U. tenuis (2–2.5 mm), but may also be pigmented. Pelvic filaments are often damaged on net-collected larvae and this pigment is rarely available, so neither the presence nor absence of pigment is diagnostic. Dorsal tail pigment occurs anterior to the area over the anus (approximately above the mid-gut) and usually stretches to mid-tail. Ventral pigment is present throughout the larval stage and is often located more closely to the anus than U. chuss and U. tenuis . Pigment is absent on the caudal area until late postflexion stage (7–10 mm).

Figures

FIG. 2. Line illustrations of dorsal view showing location of head and dorsal midline pigment of (A) 2.2 mm Urophycis chuss, (B) 2.7 mm Urophycis regia, and (C) 1.9 mm Urophycis tenuis.

FIG. 3. Line illustrations of ventral view showing lower jaw and ventral midline pigment of (A) 2.2 mm Urophycis chuss, (B) 2.7 mm Urophycis regia, and (C) 1.9 mm Urophycis tenuis.

FIG. 4. Line illustrations and images of Urophycis regia at (A) 2.7 mm, (B) 3 mm, (C) 4.2 mm, and (D) 6.1 mm.