Neoleptastacus gussoae ( Cottarelli, 1973a ), 2008

Sak, Serdar, Karaytuğ, Süphan & Huys, Rony, 2024, Review of Neoleptastacus Nicholls, 1945 (Harpacticoida, Arenopontiidae), including an updated key to species and proposal of Phreatipontia gen. nov., Zootaxa 5525 (1), pp. 1-66 : 25

Neoleptastacus gussoae ( Cottarelli, 1973a)

Arenopontia gussoae Cottarelli, 1973a

Arenopontia (Neoleptastacus) gussoae Cottarelli, 1973a : Bodin (1979: 124)

Neoleptastacus gussoae ( Cottarelli, 1973a) Sak et al. (2008: 412)

Original description. Cottarelli (1973a): 49–56; Figs 1 –21.

Type locality. Cuba, Matanzas Province; north coast, 3 km from Varadero, Playa Arenas Blancas ; sandy beach.

Body length. 317 μm (♀), 281 μm (♂).

Remarks. Cottarelli (1973a) claimed that the mandibular palp displays a 2-segmented endopod and used it to differentiate the species from N. acanthus and N. indicus . Although the endopod has been illustrated as 2-segmented in several contemporary arenopontiid descriptions with the boundary between both segments often ill-defined (e.g. Mielke 1982b, 1985, 1987), others have shown it to be clearly 1-segmented ( Itô 1978; Mielke 1982a; Wells & Rao 1987; Sak et al. 2008, 2024). The validity of the observations of a 2-segmented condition and the usefulness of mandibular endopod segmentation as a species discriminant are questionable since it is generally assumed that this ramus is primitively 1-segmented in the Harpacticoida ( Huys & Boxshall 1991) . The alleged presence of an outer basal seta on P1–P2 and the absence of an inner basal spine on P 1 in the original description are based on observational errors. The linear egg-sac typically contains 3– 5 eggs. Species discrimination in the gussoae -subgroup is notoriously difficult, however N. gussoae can be differentiated from the other two members ( N. abbreviatus sp. nov., N. chilensis sp. nov.) that have both the anal processes and terminal extensions of the caudal rami dorsally recurved, by the elongate P1 endopod (1.30 times as long as exopod vs 0.85–1.00) and the shorter and broader female P5 (length/maximum width ratio 2.0 vs 2.4–2.6) ( Table 4 ).

Neoleptastacus gussoae is so far known only from several sandy beaches in the Matanzas Province in Cuba. In addition to the type locality ( Cottarelli 1973a), the species was also recorded from the Varadero beach on the Península de Hicacos, and from Playa Sirena of Cayo Largo, a small resort island 80 km south of the Península de Zapata ( Mielke 1988).

Mielke(1982 b, 1987)provisionally assigned a number of populations from Panamá and Chile to the geographically closest member of the acanthus -group, as “ N.? gussoae ”. In his first report ( Mielke 1982b) he recorded the form from both the Atlantic (Comarca de Guna Yala: San Blas Islands, Isla Nalunega) and Pacific (Panamá Province: Isla Melones, Playa Nueva Gorgona and Playa Avenida Balboa) seaboards of Panamá but remained ambiguous in his view on their identity. Although he considered the presence of a gussoae -complex of cryptic species in Panamá likely since no variability within the various populations was recorded, the possibility that N. gussoae represented a highly variable species was not ruled out. Mielke (1982b) finally stated that a definitive clarification can only be obtained through cross-breeding experiments and that N. gussoae is to be considered as an amphi-American species or a species complex that is in the process of splitting. Wells (1986a-b) regarded it as a trans-Panamanian species. This view is not accepted here (see below N. abbreviatus sp. nov. and N. rectus sp. nov.).

In contrast to the Panamanian material, considerably more morphological uniformity was found in the widely disjunct populations of the so-called “normal form” ( Mielke, 1987) of N.? gussoae along the Chilean coast (Coquimbo, Antofagasta, Iquique). Mielke (1987) distinguished a second form which co-occurs with the “normal form” in at least Coquimbo and Iquique and differs in the wider rostrum, spinulation of the inner spinous process of P5, sharper and not dorsally recurved spinous processes on the anal somite, and absence of a dorsal spur and different insertion site of seta III on the caudal ramus. Breeding experiments are needed to confirm or disprove the conspecificity of these two co-occurring forms. Except for the anal somite and caudal ramus in lateral aspect, Mielke (1987) did not provide any illustrations of the second form, however, the normal form is here treated as a distinct species, N. chilensis sp. nov. (see below).

Figures

FIGURE 1. Neoleptastacus acanthus (Chappuis, 1954) (♀): (A) habitus, dorsal; (B) habitus, lateral; (C) rostrum, dorsal.