Penaeus (Eopenaeus), 2023

Chan, Tin-Yam, 2023, New subgeneric names for the most commercially important shrimp genus Penaeus Fabricius, 1798 (Crustacea, Decapoda, Penaeidae), ZooKeys 1141, pp. 29-40 : 29

Penaeus (Eopenaeus) subgen. nov.

Type species.

Penaeus semisulcatus De Haan, 1844.

Gender of subgenus.

Masculine.

Diagnosis.

Rostrum generally bearing 3 or 4 ventral teeth. Median sulcus on postrostral carina present or absent. Adrostral sulcus extending posteriorly more or less to level of epigastric tooth. Gastrofrontal carina absent. Cervical carina with dorsal end a distance from dorsal carapace. Hepatic carina distinct and usually sloping anteroventrally. First pereiopod with distinct ischial spine. Fifth pereiopod bearing exopod. Sixth abdominal somite completely lacking dorsolateral sulcus. Telson without lateral spines. Thelycum closed.

Etymology.

The name Eopenaeus (from the Greek Eos for others) refers to this subgenus being morphologically close to the nominotypical subgenus of Penaeus while the molecular data revealed that this subgenus is actually more derived than Penaeus (Penaeus) ( Yang et al. 2023).

Species included.

Penaeus (Eopenaeus) esculentus Haswell, 1879, Penaeus (Eopenaeus) semisulcatus De Haan, 1844.

Remarks.

This taxon corresponds to "gen. nov.1" in the 11-genus scheme of fig. 3 in Yang et al. (2023). Morphologically this subgenus is similar to Penaeus (Litopenaeus) . Other than having different types of thelycum, these two subgenera can be distinguished by the body coloration [banded in Penaeus (Eopenaeus) subgen. nov. but not banded in Penaeus (Litopenaeus) ] and the development of the dorsolateral sulcus on the sixth abominal somite [weak to distinct in Penaeus (Litopenaeus) but completely absent in Penaeus (Eopenaeus) subgen. nov.]. Pérez Farfante (1969) and Pérez Farfante and Kensley (1997) also pointed out that there are differences in the shape of the petasma between these two subgenera, with the ventral costa reaching or not reaching the distal margin of the lateral lobe in Penaeus (Eopenaeus) subgen. nov. and Penaeus (Litopenaeus) , respectively.