Galathea arani, Macpherson & Rodríguez-Flores & Machordom, 2025

Macpherson, Enrique, Rodríguez-Flores, Paula C. & Machordom, Annie, 2025, New species of Galathea Fabricius, 1793 and Nanogalathea Tirmizi & Javed, 1980 (Crustacea: Decapoda, Galatheidae) from the Western Pacific, Zootaxa 5570 (3), pp. 447-483 : 448-453

Galathea arani sp. nov.

( Figs. 1 , 2 , 3B )

Material examined. Holotype: New Caledonia, KANACONO, Stn DW 4705, 22°46’S, 167°19’E, 17 August 2016, 290– 317 m: F 5.1 mm (MNHN-IU-2017-11657).

Paratypes: Papua-New Guinea, KAVIENG, Stn CP 4457, 02°33’S, 150°41’E, 02 September 2014, 133– 178 m: 1 M 4.2 mm (MNHN-IU-2014-8124) .

New Caledonia, SPANBIOS, Stn CP 5113, 21°10.1’S, 165°51.1’E, 28 June 2021, 260– 260 m: 1 F 5.5 mm (MNHN-IU-2020-3563) .

Etymology. This species is dedicated to the first author’s grandson, Aran, for his enormous love of marine animals.

Description. Carapace: As long as broad; cervical groove slightly distinct, laterally bifurcated; 1 epigastric ridge medially and laterally interrupted; 1 protogastric ridge medially interrupted, not reaching laterally to lateral margin, 1 median short scale between epigastric and protogastric ridges and 1 median scale between protogastric and mesogastric ridges; 1 mesogastric and 1 metagastric ridge both medially and laterally interrupted not continuing to anterior branquial ridges, several minute scales behind metagastric ridge. Posterior branchial region with 5 interrupted transverse ridges, sometimes 1 ridge uninterrupted. Lateral margins convex medially, with 6–7 spines: 2 spines in front of and 4–5 spines behind anterior cervical groove; first anterolateral, second small, accompanying another spine ventral to between first and second; 2 spines on anterior branchial margin, and 2–3 spines on posterior branchial margin, last minute or absent. External orbital limit ending in minute spine; infraorbital margin with 1-2 spines. Rostrum broad triangular, 1.4 times as long as broad, length 0.6 postorbital carapace length and breadth 0.4 that of carapace, nearly horizontal in lateral view; distance between distalmost lateral incisions 0.2 distance between proximalmost lateral incisions; dorsal surface with some short setae; lateral margin with 4 deeply incised sharp teeth.

Pterygostomian flap rugose, unarmed, anterior margin blunt.

Thoracic sternum: As long as broad, lateral extremities gently divergent posteriorly. Sternite III with median shallow notch, anterior margin at each side of notch slightly convex. Sternite IV with anterior part as wide as sternite III, with some minute striae. Sternites IV–VI with a few striae on lateral sides. Sternite III ~ 2.2 × as wide as long; sternite IV nearly 2.7 × as wide as long, and 2.8 × as wide as sternite III.

Pleon: Tergites II and III each with 2 transverse ridges on tergite, anterior ridge more distinctly elevated than posterior ridge; tergite of somites IV–V smooth or with short scales; somite VI with 2 medially interrupted ridges, posteromedian margin straight. Males with G1 and G2.

Eye: Ocular peduncles 1.4 times longer than broad, maximum corneal diameter 0.6 rostrum width.

Antennule: Article 1 with 3 well-developed spines, distodorsal larger. Ultimate article with a few short fine setae on distodorsal margin.

Antenna: Article 1 with distomesial spine reaching end of article 2. Article 2 with 2 distal spines, distolateral spine subequal or larger than distomesial, reaching or overreaching article 3. Article 3 with distomesial spine.

Mxp3: Ischium with well-developed distal spine on extensor and flexor margins; crista dentata with 12–13 denticles. Merus equally long as ischium; flexor margin with 2 subequal strong spines; extensor margin with distal spine. Carpus unarmed.

P1: 2.7 times carapace length, relatively slender, somewhat depressed on palm, more so on fingers. Merus as long as carapace, 1.5 times as long as carpus, with spines arranged roughly in rows, distal spines prominent. Carpus as long as palm, twice longer than broad; dorsal surface with small spines arranged roughly in longitudinal rows; mesial margin with 2–3 strong spines. Palm 2.5 times longer than broad, lateral and mesial margins subparallel; spines arranged roughly in rows; dorsolateral row continuing onto lateral margin of fixed finger. Fingers 0.6 times as long as palm, each finger distally with two rows of teeth and spooned; movable finger with row of distal dorsomesial spines.

P2–4: Moderately slender. P2 1.6 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P2 merus, P4 merus 0.7 length of P3 merus); P2 merus 0.8 carapace length, 4 times as long as broad, 1.5 times longer than P2 propodus. Extensor margin with row of 11–12 proximally diminishing spines on P2–3, 1 small distal spine on P4; ventral margins distally ending in strong spine followed proximally by 1–2 spines and several eminences, lateral sides with 2–5 small spines on P4. Carpi with 5–6 spines on extensor margin on P2-4; lateral surface with 3-4 spines or acute granules sub-paralleling extensor margin; flexor distal margin acute. Propodi 3.5–4.0 times as long as broad; extensor margins with 3–5 proximal spines; flexor margin with 5–6 slender movable spines, terminal spines paired. Dactyli distally ending in well-curved strong spine, length 0.5–0.6 that of propodi; flexor margin with 6–7 proximally diminishing teeth, terminal tooth prominent.

Epipods on P1–2; P2 epipod reduced.

Setae: Three types of setae were observed, (1) short plumose setae, with minute setules along both sides of shaft, densely located on ridges of carapace and pleon ( Fig. 3B ); (2) long thick simple setae, sometimes iridescent, sparsely located on carapace, pleon and P1–4; (3) short thick simple setae, sparsely located on carapace, pleon and P1–4.

Colour in life. Body colour orange, with median longitudinal whitish broad stripe, from base of rostrum to pleonal somite V; one whitish lateral stripe on each branchial region. P1–4 orange, with diffuse whitish band at distal part of propodi; distal part of P2–4 dactyli reddish.

Genetic data. COI and 16S.

Remarks. The new species belongs to the group of species characterized by having all gastric ridges medially and laterally interrupted or scale-like, and the absence of dorsal spines on the branchial regions. The morphologically and genetically closest species is G. lemniscata Macpherson & Robainas-Barcia, 2015 , from New Caledonia and Chesterfield Islands. Both species can be distinguished by the following characters:

—The scale-like ridges on the meta- and mesogastric areas are arcuate in G. lemniscata , whereas these ridges are transverse and not arcuate in the new species.

—The P2–4 meri are 2.5–2.7 times as long as broad in G. lemniscata , whereas they are 4 times as long as broad in G. arani .

—The short setae on the carapace and pleon are simple, without setules, in G. lemniscata ( Fig. 3A ), whereas these setae have short setules along both sides of the shaft in G. arani ( Fig. 3B ).

Morphologically, the new species is also close to G. poupini Macpherson & Robainas-Barcia, 2015 , from the French Polynesia. The main difference between the new species and G. poupini is the presence of epigastric spines in G. poupini , whereas these spines are absent in the new species.

Genetically, the new species can be distinguished from G. lemniscata . The new species diverges from G. lemniscata by 2.33% for 16S and 10.03% for COI. No genetic data are available for G. poupini .

Distribution. New Caledonia and Papua-New Guinea, 133– 317 m.

Figures

FIGURE 1. Galathea arani sp. nov., holotype, female, 5.1 mm, MNHN-IU-2017-11657, New Caledonia: A, carapace and pleon, dorsal view; B, sternal plastron, sternites 3 and 4; C, cephalic region, showing antennular and antennal peduncles, ventral view; D, right Mxp3, lateral view; E, right P1, dorsal view; F, right P2, lateral view; G, right P3, lateral view; H, right P4, lateral view. Scale bar: A, E–H = 1.0 mm; B–D = 0.4 mm.

FIGURE 2. Galathea arani sp. nov., paratype, female, 5.5 mm, MNHN-IU-2020-3563, New Caledonia. Dorsal view, colour in life.

FIGURE 3. Setae on dorsal carapace surface: A, Galathea lemniscata Macpherson & Robainas-Barcia, 2015, short simple setae; B, G. arani sp. nov., short plumose setae, with setules along both sides of shaft; C, G. bicornis sp. nov., long thick plumose seta, with setules along distal part of shaft, distally forming a tuft.