Aniptumnus neolaevis (Deb, 1986) Hari & Hershey & Mendoza, 2022

Hari, P. Praved, Hershey, N. Regina & Mendoza, Jose Christopher E., 2022, On two species of Aniptumnus Ng, 2002 (Crustacea: Brachyura: Pilumnidae) from India, with a description of a new species from the coast of Kerala, Zootaxa 5214 (2), pp. 261-272 : 263

Aniptumnus neolaevis (Deb, 1986) comb. nov.

Heteropanope neolaevis Deb 1995: 220 ; 1999: 374, figs. 3, 4.— Ng et al. 2018: 475, 481–482.—Trivedi et al., 2018: 59 (list).

Aniptumnus quadridentatus, Trivedi et al. 2021: 12 , figs. 7, 8, 10G–I. [Not Aniptumnus quadridentatus ( De Man, 1895) ].

Type locality. Matla River estuary, West Bengal, India .

Diagnosis. Carapace transversely subhexagonal, broader than long; anterolateral margins divided into 4 teeth posterior to exorbital angle, first low, lobiform, second to fourth more projecting. Male thoracic sternum with small section of sternite 8 exposed when pleon locked onto thoracic sternum. Pleonal somite 2 much narrower than somite 1. Chelipeds distinctly unequal, minor chela distinctly more granulate, setose than major chela. Posterodistal margin of P5 basis-ischium, with several closely packed conical tubercles; posteroproximal margin of P5 merus with few large, conical tubercles proximally gradually being replaced by smaller granules distally until proximal two-thirds of merus. G1 sinuous, distal tip bluntly round, without scoop-shaped apical lobe.

Remarks. Heteropanope neolaevis was originally described by Deb (1995: 220) based on several specimens (“50 examples”) collected from the Matla River, in the Gangetic Delta, West Bengal, India. The identity and taxonomy of this species has been extensively discussed by Deb (1999), Ng et al. (2018), and Trivedi et al. (2021). As Deb (1985) did not indicate a holotype, all of her specimens were syntypes. As such, to stabilize the taxonomy, Trivedi et al. (2021) designated one of the surviving male syntypes deposited in the collection of the Zoological Survey of India (ZSI) in Kolkata, India, as the lectotype and four other male syntypes as paralectotypes (ZSI-C1503/2). They provided detailed photographs and drawings of the lectotype as well ( Trivedi et al. 2021: figs. 7, 8, 10G–I). They further remarked that the type material of H. neolaevis agreed well with the descriptions and figures of Aniptumnus quadridentatus ( De Man, 1895) , citing the similar morphology of the carapace, pereopods, and male thoracic sternite 8, and concluded that the two nominal taxa were conspecific. They also noted, however, that while the G1 of H. neolaevis ( Trivedi et al. 2021: fig. 10G, H) closely resembled that of A. quadridentatus , the distal tip of the former is “more rounded and less produced, but this can be explained by variation” ( Trivedi et al. 2021: 14).

Comparison with the illustrations of the lectotype of A. quadridentatus and actual specimens (N = 44) from Singapore and Malaysia, however, has revealed that the G1 of adult males always has a short but distinct, scoopshaped apical lobe that is somewhat perpendicular to the long axis ( Fig. 5F–I ; cf. Ng 2002: fig. 1F, G), and none had the morphology of H. neolaevis , wherein the well-produced, distal scoop-shaped apical lobe of the G1 is absent (cf. Deb 1999: fig. 4; Trivedi et al. 2021: fig. 10G–I). Furthermore, the lectotype of H. neolaevis has a narrower pleonal somite 2, and a much larger section of sternite 8 exposed ( Trivedi et al. 2021: fig. 8D) whereas in A. quadridentatus pleonal somite 2 is wider and sternite 8 is either minimally exposed ( Fig. 5E ) or not at all (cf. Takeda 2001: fig. 3E). As such, we consider H. neolaevis to be a valid species of Aniptumnus distinct from A. quadridentatus .

Figures

FIGURE 5. Aniptumnus quadridentatus (De Man, 1895), male, 11.1 by 7.4 mm (ZRC 2021.0421), off Pulau Ubin, Singapore. A, carapace, dorsal view; B, third maxillipeds, external view; C, cephalothorax, frontal view; D, anterior thoracic sternum and pleon, ventral view; E, pleonal somites 1–3 and thoracic sternite 8, posteroventral view; F–I, left G1 (F, pleonal/ventral view; G, mesiosternal/mesiodorsal view; H, lateral view; I, sternal/dorsal view). Scale bars: 2.0 mm (A, C); 1.0 mm (B, D, E); 0.5 mm (F–I).