Samadinia hela Davie & Lee 2023, sp. nov.
Creators: name: Davie, Peter J. F.
name: Lee, Bee Yan
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Epialtidae
Samadinia
Samadinia hela

description: Samadinia hela sp. nov.
(Figs. 1A–H, 2A–C, 3A–D)
Type material. HOLOTYPE: male (12.7 × 10.2 mm) (QM-W16967), stn 85, Cruise C 0685, north-east of Townsville, Queensland, 18°05.9’S 147°10.8’E, 240–248 m, coll. R. V. Soela, 8 December 1985. PARATYPE: 1 female (16.6 × 11.5 mm) (QM-W16968), same data as holotype.
Description. Carapace pyriform; with thick tomentum of closely-set, hooked setae; patches of longer hooked setae on protogastric and lateral branchial regions. Pseudorostral spines nearly as long as carapace, straight, diverging, V-shaped. Supraorbital eave fused to carapace with straight margin; laterally flattened triangular pre-orbital spine inwardly curved, extending anteriorly at base of pseudorostral spines; postorbital lobe laterally flattened, rounded posteriorly forming cup-shape protecting eye; eyes small with darkly pigmented cornea, freely moveable (Fig. 1A, 2A).
Carapace with 7 spines and 4 large elongated plate-like spines; 1 laterally flattened hepatic plate, curved inwards, pointing at 90° to the mesobranchial plate, rounded at base; 1 mesogastric spine; 1 cardiac spine; 1 intestinal spine; 1 on each side of epibranchial region; 1 on each side of mesobranchial region; 1 lateral branchial plate laterally flattened, forwardly produced, inwardly curved, rounded at base and bluntly pointed anteriorly (Fig. 1A, C–E, 2A); 1 shorter lateral spine (broken off on left side) behind pterygostomial plate with antero-posteriorly flattened, apically widened, rounded tip (Fig. 1D, E).
Antennal flagellum shorter than pseudorostral spines; second moveable segment subequal in length to first segment. Basal antennal article comparatively narrow, with relatively straight outer margin, widest at base, outer distal angle blunt. Buccal frame square, totally covered by third maxillipeds closing buccal cavity; ischium almost twice length of merus; inner half of distal margin of ischium produced as very broad triangular lobe; merus with outer distal margin produced and rounded, superior margin concave. Pterygostomial region with short moderately projecting longitudinal plate with lobiform outer margin (Fig. 1B).
Male chelipeds stout; nearly as long as carapace length (including pseudorostral spines); ischium rounded, triangular in cross-section, with prominent blunt spine on upper distal angle; carpus narrowing distally, with blunt carinae on outer and inner margins, with blunt protuberance medio-proximally; palm of cheliped rectangular, approximately 1.75 times as long as broad (excluding fixed finger), smooth, very short, scattered setae proximally and on superior margin; moveable finger approximately 0.8 times length of palm; fingers pointed with series of low rounded teeth along cutting margins, teeth larger distally; fingers gape proximally when closed (Fig. 1H). Female chelipeds less robust, shorter than male; carinae on carpus less pronounced, surface slightly more tomentose (Fig. 2A, B). Ambulatory legs slender, covered in short tomentum, leg length decreases posteriorly; P2 longest, approximately 2.2 times carapace length (excluding pseudorostral spines), P2 slightly shorter in female (approximately 1.8 times carapace length (excluding pseudorostral spines)); merus nearly equal in length to carpus and propodus length; dactyli strong, slightly curved, with acute corneous tip (Fig. 2B).
Male thoracic sternum covered with layer of tomentum, smooth when denuded; sternites 1–4 strongly depressed, corrugated along suture lines. Female thoracic sternum smooth, sternites depressed; gonopores with flattened operculum, sternal vulvar cover not obvious (Fig. 2B, C).
Male pleon with rounded telson and 6 free somites, covered with tomentum, smooth when denuded; third somite widest, fourth to seventh somites evenly tapering (Fig. 1B, F, G). Adult female pleon rounded, with all 6 somites and telson free.
G1 straight, relatively broad, only slightly tapering; tip flattened, obliquely truncate, acutely pointed (Fig. 3A–D).
Colouration. No live colour was recorded; following preservation, specimens are uniformly dirty yellow, but with white fingers on the chelae.
Etymology. The flattened hepatic and branchial plates are reminiscient of the crown of flattened horns depicted on the fictional Marvel comic-book and film character Hela, the Asgardian goddess of death (in turn derived from Hel, a character in Norse mythology). The name is used as a noun in apposition.
Remarks. Samadinia hela n. sp. is distinctive in having very long pseudorostal spines, which are longer than the maximum carapace length (excluding the spines); slender preorbital spines that are curved inwards over the base of the rostrum; and the long and laterally flattened hepatic and lateral branchial spine plates (Fig. 1A–E, 2A).
The laterally flattened and upwardly pointing hepatic plate of Samadinia hela n. sp. is morphologically most similar to S. cidaris (Lee, Richer de Forges & Ng, 2019) (see Lee et al. 2019: fig. 7C), S. despereaux (Lee, Richer de Forges & Ng, 2019) (see Lee et al. 2019: fig. 8C), S. kotakae (Takeda, 2001) (see Richer de Forges & Ng 2013: fig. 7; Lee et al. 2017: fig. 8A), and S. strangeri (Serène & Lohavanijaya, 1973) (see Lee et al. 2017: fig. 8A, 9C, F), however the hepatic plate is much more elongated and curved inwards on S. hela n. sp. (Fig. 1A, C) compared to those species. Samadinia hela n. sp. also differs from these species in having long laterally flattened and forwardly pointing lateral branchial spines, and seven spines on the carapace (Fig. 1A–E, 2A). Samadinia cidaris, has long lateral and outward pointing branchial spines on the carapace (see Lee et al., 2019: fig. 7C). Samadinia despereaux has long lateral branchial spines, with only small granules and two spines on the carapace (see Lee et al. 2019: fig. 8C). Samadinia kotakae has long lateral branchial spines, and five short spines on the carapace (see Richer de Forges & Ng 2013: fig. 7; Lee et al. 2017: fig. 8A). Samadinia strangeri has relatively shorter lateral and outwardly pointing branchial spines, and 13 spines on the carapace (see Lee et al. 2017: fig. 8A, 9C, F).
Laubierinia globulifera (Wood-Mason, 1891) and Oxypleurodon velutinum (Miers, 1886) (Miers 1886: pl. 6 fig. 2; Guinot & Richer de Forges 1985: pl. 10 fig. A, B) are also similar to S. hela n. sp. in having a prominent preorbital eave, and elongated flattened hepatic plates (Fig. 1A, C). However, S. hela n. sp. differs importantly from those species because it has a large anteriorly directed lateral branchial plate (a modified meso-branchial spine), whereas the analogous branchial plate of the other two species is greatly reduced to merely a small tongue on the lateral carapace wall above the coxa of the cheliped.
Distribution. Only known from the type locality off northeastern Queensland, Australia. Known depth range: 240– 248 m.
description: Published as part of Davie, Peter J. F. & Lee, Bee Yan, 2023, A new species and new record of Samadinia Ng & Richer de Forges, 2013 (Crustacea: Brachyura: Epaltidae) from deepwater off north-eastern Queensland, Australia, pp. 393-400 in Zootaxa 5249 (3) on pages 394-398, DOI: 10.11646/zootaxa.5249.3.5, http://zenodo.org/record/7691091