Pseudohelice annamalai, Prema & Hsu & Shih & Ravichandran, 2022

Prema, Mani, Hsu, Jhih-Wei, Shih, Hsi-Te & Ravichandran, Samuthirapandian, 2022, Fig. 6 in Garypus sanasai Lin, Huang & Chang 2022, sp. nov., Zoological Studies 61 (56), pp. 1-13 : 2-7

Genus Pseudohelice Sakai, Türkay & Yang, 2006

Pseudohelice annamalai n. sp. ( Figs. 1 , 2 , 4 ) urn:lsid:zoobank.org:act:A5E686EC-C98A-48CF-81DF-47F1EBB3DF32

Material examined: Holotype: 1 male (17.3 × 14.6 mm) ( CASAU CR-1011 ), Vellar River estuary, Tamil Nadu, India, coll. M. Prema and S. Ravichandran, 28 Feb.–5 Mar. 2022 . Paratypes (same locality as holotype): 1 male (18.9 × 15.2 mm) ( CASAU CR- 1013), 21 Sep. 2020; 2 males (20.1 ×16.8, 16.7 × 14.0 mm) ( CASAU CR- 1014), 17 Dec. 2021; 2 males (16.4 × 13.1, 15.2 × 13.9 mm) ( CASAU CR- 1015), 25 Feb. 2022; 2 males (18.7 × 15.4, 16.7 × 14.5 mm) ( CASAU CR- 1016), 2 Mar. 2022; 2 females (18.3 × 15.4, 17.7 × 14.2 mm) ( CASAU CR- 1017), 5 Jun. 2021; 2 females (17.5 × 16.0, 10.4 × 9.5 mm) ( CASAU CR- 1018), 3 Mar. 2022, coll. M. Prema; 3 males (18.2 × 15.3, 16.7 × 14.3, 14.3 × 11.9 mm) (NCHUZOOL 17048), coll. M. Prema and S. Ravichandran, 12 Dec. 2020; 5 males (16.6 ×14.4, 18.2 × 15.9, 16.6 × 14.2, 17.1 × 14.3, 17.1 × 14.4 mm), 2 females (14.3 × 12.5, 13.9 × 11.6 mm), 1 ovig. female (18.8 × 15.3 mm) (NCHUZOOL 17049), coll. M. Prema and S. Ravichandran, 28 Feb.–5 Mar. 2022; 2 males (16.9 × 14.2, 17.2 × 14.5 mm), 2 females (15.6 × 13.2, 18.1 × 15.4 mm) ( ZRC 2022.0189), coll. M. Prema and S. Ravichandran, 28 Feb.–5 Mar. 2022.

Comparative material: Pseudohelice subquadrata and P. latreillii (see material examined in Hsu et al. 2022a).

Description: Carapace ( Fig. 2A ) quadrate, slightly broader than long, 1.08–1.15 times as broad as long; surface convex, irregularly punctated and finely granulated; mesogastric and protogastric regions deeply low with noticeable epigastric groove. Frontal margin slightly concave. Anterolateral margins with 3 teeth including larger orbital tooth, second tooth slightly narrower than preceding, last tooth very small, distinct. Infraorbital ridge ( Fig. 2C–E ) heteromorphic in both sexes; in male, mesial part with 4 or 5 rounded, smooth, less interspaced small tubercles, followed by several large, elongated and less convex tubercles; lateral part with 1 significantly largest, very convex and elliptical tubercle, followed by 1 less convex tubercle, and 2 or 3 large convex tubercles ( Fig. 2C ); in female form I, mesial part with several (5 or 6) dense, small rounded tubercles, followed by several larger, less convex elongated tubercles; lateral part with well-spaced 3 or 4 elliptical, more convex, larger tubercles, ending with 1 or 2 small rounded tubercles ( Fig. 2D ); in female form II, mesial part with several (5 or 6) dense, small rounded tubercles, followed by well-spaced several elongated and less convex tubercles, lateral part with 1 significantly largest elongated tubercle, and 2–5 closely spaced, larger tubercles ( Fig. 2E ).

Chelipeds ( Fig. 2B ) usually unequal in adult male and equal in some adult male (similar size) and all female; palm bulky, inner palm meagerly granulated, outer surface smooth, line of short setae present at base of anterior margin of palm.

Ambulatory legs ( Fig. 1A‒D ) slender, anterior margins of merus, carpus, and propodus covered with short setae, posterior margins with sparse short setae.

Male G1 ( Fig. 2F‒I ) slender, tapering, slightly curved towards lateral end in distal part, chitinous endpiece shorter, wider and thicker, bilobed and rounded end; female vulvae ( Fig. 2J, K ) with a semicircular sternal vulvar cover; sunken on inner part.

Size: Largest male specimen is CW 20.1 mm ( CASAU CR- 1014); largest female is (ovigerous) CW 18.8 mm (NCHUZOOL 17049).

Color in life: Varied from dark purple to dark gray, with irregular light brown, yellowish brown, or white patches on posterior carapace and some individuals on entire carapace as white dots or patches; some young individuals yellowish orange-brown. Chelipeds usually lighter brown (most of surface) and upper regions of palm lighter purple in adult male ( Fig. 4A–G ).

Ecological notes: In the southeastern coast of India, this species inhabits sand-muddy banks of mangroves ( Fig. 3 ) and it is sympatric with A. annulipes (H. Milne Edwards, 1837) . Some burrows ( Fig. 4H ) were located near the pneumatophores of Avicennia mangroves. Burrows have a depth of 25–30 cm and are branched, with larger-sized pellets around the burrow entrance.

Etymology: This species is named after Annamalai University, in honor of 100 years’ service in education and research as a state university of India. In addition, the present specimens were collected from the intertidal areas in front of the Faculty of Marine Science, Research Centre (Centre of Advanced Study in Marine Biology, Annamalai University), Vellar River, Tamil Nadu. The name is used as a noun in apposition.

Distribution: Currently known only from the type locality, the Vellar River estuary, southeastern India.

Remarks: Morphologically, this new species is similar to P. subquadrata and P. latreillii , but can be distinguished by the infraorbital ridges, male G1s, and female vulvae. Both infraorbital ridges and male G1s (or female vulvae) should be compared to identify the species of Pseudohelice , because male infraorbital ridges and female vulvae are similar in P. annamalai and P. subquadrata , and male G1s and female infraorbital ridges are similar in P. annamalai and P. latreillii ( Table 2).

Pseudohelice annamalai can be discerned from P. subquadrata by the infraorbital ridges in both sexes and male G1s. In P. annamalai , the lateral part of male infraorbital ridge has 1 less convex but obvious tubercle between the largest tubercle and 2 or 3 large convex tubercles (vs. this tubercle absent or not obvious in P. subquadrata ) ( Fig. 2C ; Hsu et al. 2022a: fig. 1E); the lateral part of the female infraorbital ridge lacks the largest elongated tubercle (form I) or is present but smaller and less convex (form II) (vs. largest tubercle relatively larger and more convex in P. subquadrata ) ( Fig. 2D, E ; Hsu et al. 2022a: fig. 1F). Pseudohelice annamalai has the G1 slender, the upper part tubular, the chitinous endpiece with distal part shorter and thicker (vs. G1 stouter, upper part slightly flatter, chitinous endpiece with distal part relatively longer and thinner in P. subquadrata ) ( Fig. 2F–I ; Hsu et al. 2022a: fig. 1G–J).

Pseudohelice annamalai can be differentiated from P. latreillii by the male infraorbital ridges and the female vulvae. In P. annamalai , the lateral part of male infraorbital ridge has 1 less convex but obvious tubercle between the largest elliptical tubercle and 2 or 3 large convex tubercles (vs. tubercle absent between the largest rounded tubercle and 2 or 3 large convex tubercles in P. latreillii ) ( Fig. 2C ; Hsu et al. 2022a: fig. 3E). In females, the sternal vulvar cover is often longer (but shorter in some individuals) in P. annamalai (vs. shorter in P. latreillii ) ( Fig. 2J–K ; Hsu et al. 2022a: fig. 1L, M).

Molecular analyses

We used 16 specimens from the Vellar River estuary for molecular study, with 8 haplotypes of COI ( Table 1). The pairwise nucleotide divergences of K2P distances and bp differences among haplotypes of the species of Pseudohelice are shown in table 3. The intraspecific nucleotide divergences (and bp differences) of P. subquadrata , P. annamalai n. sp., and P. latreillii are ≤ 1.39% (≤ 9 bp), ≤ 0.77% (≤ 5 bp), and ≤ 1.86% (≤ 12 bp), respectively. Pseudohelice annamalai has interspecific divergences ≥ 1.54% (≥ 10 bp) with P. subquadrata and ≥ 3.45% (≥ 22 bp) with P. latreillii .

The phylogenetic tree ( Fig. 5 ) based on COI shows three clades within the genus Pseudohelice , corresponding to P. subquadrata , P. annamalai , and P. latreillii , although P. annamalai is not highly supported by BI and MP methods. The relationship between P. subquadrata and P. annamalai is closer, but the support values are not high in BI and MP methods.

Figures

Fig. 1. Pseudohelice annamalai n. sp. with preserved coloration. A, dorsal view of male; B, ventral view of male; C, dorsal view of female; D, ventral view of female. A, B, holotype, CASAU CR-1011 (17.3 × 14.6 mm); C, D, NCHUZOOL 17049 (14.3 × 12.5 mm).

Fig. 2. Pseudohelice annamalai n. sp. A, carapace; B, outer view of male left cheliped; C, left male infraorbital ridge; D, E, left female infraorbital ridge (D, form I; E, form II); F, G, dorsal view of right G1; H, I, ventral view of right G1; J, K, right vulva (J, form I; K, form II). A, B, male, CASAU CR-1013 (18.9 × 15.2 mm); C, F–I, holotype male, CASAU CR 1011 (17.3 × 14.6 mm); D, female, NCHUZOOL 17049 (18.8 × 16.4 mm); E, J, female, ZRC 2022.0189 (18.1 × 15.4 mm); K, female, NCHUZOOL 17049 (13.9 × 11.6 mm).

Fig. 4. Color in life of Pseudohelice annamalai n. sp. (A–G) from higher intertidal zone of the Vellar River estuary, Tamil Nadu, India. A, B, dorsal view of male; C, D, frontal and dorsal views of female, respectively; E, F, dorsal and frontal views of an ovigerous female, respectively; G, male at the burrow entrance near mangrove pneumatophores; H, burrow in the habitat. A, CASAU CR-1012 (18.2 × 15.5 mm); B, CASAU CR-1016 (18.7 × 15.4 mm), C–F, specimens not collected; G, NCHUZOOL 17049 (18.2 × 16.8 mm).

Fig. 3. Habitats of Pseudohelice annamalai n. sp. A, higher intertidal zone of the Vellar River estuary, in front of the Centre of Advanced Study in Marine Biology, Tamil Nadu, southeastern India; B, artificial mangroves of Rhizophora sp. and Avicennia sp., in the margin of Vellar River.

Fig. 5. A Bayesian inference (BI) tree for species of Pseudohelice and the outgroups, based on the cytochrome c oxidase subunit I (COI) gene. Probability values at the nodes represent support values for BI, maximum likelihood (ML) and maximum parsimony (MP). For haplotype names, see table 1.