Neoleptastacus spinicaudatus Nicholls, 1945

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 : 11

Neoleptastacus spinicaudatus Nicholls, 1945

Paraleptastacus spinicaudatus Nicholls, 1945 : lapsus calami by Chappuis (1954: 269)

Arenopontia spinicaudata ( Nicholls, 1945) Chappuis (1955: 56)

Arenopontia (Neoleptastacus) spinicaudata ( Nicholls, 1945) : Wells (1967: 324)

Neoleptastacus longipes Nicholls, 1945 : lapsus calami by Karanovic (2008: 5, 331)

Original description. Nicholls (1945): 22–23; Text fig. 3.

Additional description. Sak et al. (2008): 435–441; Figs 13–17 .

Type locality. Australia, Western Australia. Nicholls (1945) did not specify a type locality but collected the species from two sandy beaches some 500 km apart. The first, Leighton Beach (in the vicinity of Perth), was sampled in October 1939 while samples from the second site, locally known as ‘Back Beach’ at Dongarra, were collected in March 1940. All syntypes deposited at the Natural History Museum in London originated from Back Beach which was designated as the type locality by Sak et al. (2008).

Body length. 280–300 μm (both sexes) [ Nicholls 1945].

Remarks. Sak et al. (2008) re-examined the type material and redescribed both sexes in detail. Nicholls’s (1945) original description is adequate by contemporary standards except for the reported absence of the inner seta on P4 exp-3, an error that was perpetuated in some morphological comparisons ( Noodt 1955b; Bodiou & Colomines 1996) and identification keys ( Lang 1965; Karanovic 2000; Wells 2007). Within the spinicaudatus - group, N. spinicaudatus is morphologically closest to N. spicatus , both of which exhibit a dorsolateral spur near the base of caudal ramus seta VII. The type species can be differentiated from N. spicatus by the shape of the abdominal hyaline frills (lappets denticulate vs semi-incised obtusidigitate), the proportional size of the inner distal seta on P2–P3 enp-2 (shorter vs longer than endopod) and the morphometric dimensions of the P5 (2.5 times as long as wide vs 3.0 times). The apical spinous process on the P5 of both sexes is minutely bipinnate in N. spinicaudatus (and still delimited at its base on the posterior surface in the ♀) while it is lacking such ornamentation in N. spicatus (and completely fused to the segment in the ♀). The linear egg-sac typically contains 2–4 large eggs; occasionally six eggs are found in which case they overlap ( Nicholls 1945).

The species is so far known only from two sandy beaches in Western Australia ( Nicholls 1945). Chappuis (1954: 269) claimed to have found one female and one male in Annaba (= Bône) in northeastern Algeria which closely resemble N. spinicaudatus but did not present any illustrations to substantiate his record. In a later report, Chappuis (1958: 414, Figs 2–5 ) provided illustrations of the female antennule, P2 endopod, P5 and caudal ramus of specimens he collected in Puget Sound, Washington State. Despite differences in the P5, length of P3–P4 endopods and caudal rami, Chappuis (1958) assigned his material to N. spinicaudatus , stating that such morphological minutiae do not warrant the proposal of a distinct subspecies. As pointed out by Sak et al. (2008), the morphology of the fifth legs suggests that Chappuis (1958) was almost certainly dealing with Mesopontia dillonbeachia ( Lang, 1965) . Karanovic (2008) erroneously cited the species as Neoleptastacus longipes Nicholls, 1945 .

Figures

FIGURE 2. Neoleptastacus acanthus (Chappuis, 1954): (A) habitus (♂), dorsal; (B) anal somite and caudal rami (♀), dorsal; (C) anal somite and left caudal ramus (♀), lateral; (D) antenna (♀), medial; (E) antennary endopod (♀), outer. [Lateral spines of antennary endopod indicated by arrows in D–E]

FIGURE 3. Neoleptastacus acanthus (Chappuis, 1954): (A) antennule (♀), dorsal; (B) antennule (♂), ventral. [spatulate setae indicated by arrows]

FIGURE 4. Neoleptastacus acanthus (Chappuis, 1954) (♀): (A) P1, anterior; (B) P2, anterior; (C) P3, anterior; (D) P4, anterior.

FIGURE 5. Neoleptastacus acanthus (Chappuis, 1954): (A) urosome (♀), ventral [caudal ramus seta V figured at full length in inset]; (B) urosome (♂), ventral.

FIGURE 13. Phreatipontia phreatica (Cottarelli, Bruno & Venanzetti, 1994) comb. nov.: (A) antennule (♀), dorsal; (B) antenna (♀), medial [lateral endopodal spines indicated by arrows]; (C) antenna (♀), outer; (D) antennule (♂), anterior; (E) antennule (♂), dorsal.

FIGURE 14. Phreatipontia phreatica (Cottarelli, Bruno & Venanzetti, 1994) comb. nov. (♀): (A) P1, anterior; (B) P2, anterior; (C) P3, anterior; (D) P4, anterior.

FIGURE 15. Phreatipontia phreatica (Cottarelli, Bruno & Venanzetti, 1994) comb. nov.: urosome (♀), ventral.

FIGURE 16. Phreatipontia speluncae (Cottarelli, Bruno & Venanzetti, 1994) comb. nov. (♀): (A) habitus, dorsal; (B) habitus, lateral; (C) anal somite and caudal rami, dorsal [arrow indicating modified seta IV]; (D) anal somite and right caudal ramus, lateral.

FIGURE 17. Phreatipontia speluncae (Cottarelli, Bruno & Venanzetti, 1994) comb. nov.: (A) habitus (♂), dorsal; (B) antennule (♂), ventral; (C) antennule (♀), ventral; (D) antenna (♀), medial [lateral endopodal spines indicated by arrows].