Pilumnopeus A. Milne-Edwards, 1867

Patel, Krupal, Trivedi, Jigneshkumar, Mitra, Santanu & Ng, Peter K. L., 2024, The taxonomy of Heteropanope indica De Man, 1887 from the Indian Ocean, with a note on Pilumnopeus pearsei (Rathbun, 1932) (Crustacea: Decapoda: Brachyura: Pilumnidae), Zootaxa 5437 (3), pp. 384-396 : 385

Genus Pilumnopeus A. Milne-Edwards, 1867

Pilumnopeus A. Milne Edwards, 1867: 277 (

type species: Pilumnopeus crassimanus A. Milne-Edwards, 1867 = Pilumnopeus serratifrons ( Kinahan, 1856) , subsequent designation by Balss (1933)).— Balss 1933: 33.— Sakai 1939: 542.— Dell 1968: 18.— Takeda & Miyake 1969: 120 (part).— Sakai 1976: 500.— Manning & Holthuis 1981: 151.— Davie 1989: 138.— Wada 1995: 396 (key), 403.

Heteropanope — De Man 1887: 52 (part); Alcock 1898: 207 (part).

Heteropanope (Pilumnopeus) — Monod 1956: 264 (part).

Remarks. Davie (1989) diagnosed Pilumnopeus s. str. with several key characters. The most significant is that in Pilumnopeus species, the male thoracic sternites 3 and 4 are proportionately transversely narrower, with the distance between the suture between sternites 2 and 3, and that between sternites 3 and 4 subequal or slightly longer than the distance between the suture between sternites 3 and 4, and the tip of the sternopleonal cavity. In Benthopanope species, the male thoracic sternites 3 and 4 are proportionately transversely broader, with the distance between the suture of sternites 2 and 3, and that between sternites 3 and 4, is distinctly longer than the distance between the suture between sternites 3 and 4, and the tip of the sternopleonal cavity. Both genera can be separated from Heteropanope by their dorsal surface of the carapace possessing ridges and distinct regions (versus surface smooth and regions barely visible in Heteropanope ), and male thoracic sternite 8 is visible when the pleon is closed (versus sternite 8 not visible in Heteropanope ). Davie (1989) noted that Eurycarcinus A. Milne-Edwards, 1867 , was closely allied to these three genera but refrained from further taxonomic treatment given the lack of material for examination. Ng et al. (2018) subsequently revised the genus and showed that Eurycarcinus species are morphologically quite different, with a large exposed male thoracic sternite 8 when the pleon is closed (see also Trivedi et al. 2021).

Although Davie (1989: 144) transferred P. indicus to Benthopanope , he did not examine specimens or provide an explanation. The present study shows that the Heteropanope indica De Man, 1887 , is not a Benthopanope as its male sternal condition is clearly that of a Pilumnopeus . Heteropanope pearsei Rathbun, 1932 , which was synonymised by T. Sakai (1965) under P. indicus but treated as a separate species of Benthopanope by Ng et al. (2001, 2008) is also here referred to Pilumnopeus . Its taxonomy is discussed together with P. indicus below.

Pilumnopeus now comprises 11 species: P. africanus (De Man, 1902) , P. caparti ( Monod, 1956) , P. convexus (Maccagno, 1936) , P. granulatus Balss, 1933 , P. indicus ( De Man, 1887) , P. laevimanus Cano, 1889 , P. makianus (Rathbun, 1931) , P. marginatus (Stimpson, 1858) , P. pearsei ( Rathbun, 1932) , P. serratifrons ( Kinahan, 1856) and P. vauquelini (Audouin, 1826) .