Galathea lemaitrei, Macpherson, Enrique & Robainas-Barcia, Aymee, 2015

Macpherson, Enrique & Robainas-Barcia, Aymee, 2015, Species of the genus Galathea Fabricius, 1793 (Crustacea, Decapoda, Galatheidae) from the Indian and Pacific Oceans, with descriptions of 92 new species, Zootaxa 3913 (1), pp. 1-335 : 157-160

Galathea lemaitrei n. sp.

( Fig. 55 )

Material examined. Holotype: Red Sea. Sudan, Al Bahr al Ahmar. Sanganeb, SAN107, 10 m, 1 October 1992: ov. F 2.9 mm ( SMF).

Paratypes: Red Sea. Sudan, Al Bahr al Ahmar. Sanganeb, SAN107, 10 m, 1 October 1992: 4 M 2.5–2.8 mm, 3 ov. F 2.3–2.9 mm, 2 F 1.8–2.0 mm ( SMF).—SAN124, 42 m, 2 October 1992: 2 M 2.5–2.9 mm, 2 ov. F 2.5–2.8 mm, 1 F 2.5 mm ( SMF). Saudi Arabia, Farasan Banks, Dolphen Lagoon, 19.0053°N, 40.1482°E, 1–7 m, 4 March 2013: 1 M 2.5 mm (UF36560).

Etymology. Named for Rafael Lemaitre, for his major contributions to anomuran systematics.

Description. Carapace: As long as broad; transverse ridges with dense short setae; cervical groove distinct, laterally bifurcated. Gastric region with 5 transverse ridges: 1 epigastric medially interrupted, with 2 spines; 1 protogastric ridge uninterrupted, 1 parahepatic spine on each side; 1 mesogastric scale-like ridge; 2 metagastric ridges, anterior one medially interrupted, posterior ridge short. Anterior branchial region with distinct ridges. Midtransverse ridge uninterrupted, preceded by shallow cervical groove. Posterior branchial region with 4 transverse ridges, 2 of them uninterrupted. Lateral margins slightly convex medially, with 7 spines: 2 spines in front of, and 5 spines behind, anterior cervical groove; first anterolateral, well-developed, slightly behind level of lateral limit of orbit, second spine small, 1 spine ventral to between first and second spine; 2 spines on anterior branchial region, and 3 spines on posterior branchial margin. Small spine on limit of orbit; infraorbital margin with well-developed spine. Rostrum 1.6 times as long as broad, length 0.6 postorbital carapace length and breadth 0.4 that of carapace; distance between distalmost lateral incisions 0.2 distance between proximalmost lateral incisions; dorsal surface longitudinally concave, with some small setae; lateral margin with 4 deeply incised sharp teeth.

Pterygostomian flap rugose, unarmed, ridges with short setae, anterior margin acute.

Sternum: As long as broad, lateral extremities gently divergent posteriorly.

Abdomen: Somite 2 with 2 uninterrupted transverse ridges on tergite; somites 3–4 with anterior ridge only; somites 5–6 smooth, or with some scales, posteromedian margin of somite 6 straight. Males with G1 and G2.

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

Antennule: Article 1 with 3 well-developed distal spines, distodorsal larger than others. Ultimate article with tuft of fine setae on distodorsal margin.

Antenna: Article 1 with strong distomesial spine reaching or exceeding antennal peduncle. Article 2 with 2 subequal distal spines, reaching end of article 3. Article 3 with distomesial spine; article 4 unarmed.

Mxp3: Ischium with flexor and extensor margins ending in blunt point; crista dentata with 21–24 denticles. Merus as long as ischium; flexor margin with 2 spines, proximal spine larger than distal; extensor margin unarmed. Carpus unarmed.

P1: 2.4 times carapace length, somewhat depressed on palm, more so on fingers, with some setiferous scales, and some scattered long iridescent setae. Merus as long as carapace, 1.6–1.7 times as long as carpus, with some spines, dorsomesial and distal spines stronger than others. Carpus as long or slightly larger than palm, 2.4–2.5 times as long as broad; dorsal surface with some small spines; mesial margin with 2 or 3 well-developed spines, distal second much stronger than others. Palm 1.9–2.5 times longer than broad, lateral and mesial margins subparallel; well-developed spines arranged roughly in dorsal, dorsolateral and dorsomesial rows; dorsolateral row continuing along proximal part of fixed finger. Fingers as long as palm, each finger with two rows of teeth distally spooned; movable finger with some small proximal spines.

P2–4: moderately long and slender, with some setose striae and some long setae; setae non-iridescent. P2 1.8 times carapace length. Meri successively shorter posteriorly (P3 merus 0.8 length of P3 merus, P4 merus 0.8 length of P3 merus); P2 merus 0.7 carapace length, 4.5 times as long as broad, 1.4 times longer than P2 propodus. P3 merus 3.7 times as long as broad, 1.2 times longer than P3 propodus. P4 merus 3.1 times as long as broad, slightly longer than P4 propodus. Extensor margin with row of 8 proximally diminishing spines on P2–3; 1 distal spine on P4; ventral margins distally ending in strong spine, lateral side with 2 spines on P4; ventromesial margin with terminal spine on P2. Carpi with 2–4 spines on extensor margin on P2–3, 1 or 2 on P4; lateral surface with 3 or 4 small spines or acute granules sub-paralleling extensor margin; flexor distal margin with minute spine. Propodi 4.0–5.0 times as long as broad; extensor margin with 1–3 proximal spines; flexor margin with 4 or 5 slender movable spines. Dactyli distally ending in well-curved strong spine, length 0.6 that of propodi; flexor margin with 5 or 6 proximally diminishing teeth, terminal one prominent.

Epipods present on P1 and P2.

Coloration. Base color translucent light orange, with numerous minute red spots on carapace and abdomen. Carapace with some whitish large spots on each branchial region. P1 with reddish band on distal part of merus, carpus, palm and proximal part of fingers; spines reddish. P2–4 each with red and whitish bands, white band on distal part of propodus and proximal part of dactylus.

Remarks. Galathe lemaitrei n. sp. is very close to G. autahi n. sp. from the French Polynesia, Vanuatu, New Caledonia, and New South Wales. The two species can be easily distinguished by the following characters:

- The epipods are present on P1 and P 2 in G. lemaitrei , instead of only on P 1 in G. autahi . - The P1 palm has rows of well-developed spines in G. autahi , whereas these spines are minute and scattered on the dorsal surface and margins in G. lemaitrei .

- The Mxp3 merus is unarmed on the extensor margin in G. lemaitrei , while armed with a distal spine in G. autahi .

On the other hand, G. lemaitrei and G. autahi also resemble G. halia n. sp. from the Philippines to northwestern Australia, Vanuatu and New Caledonia. Nevertheless, G. h a l i a differs from G. l e m a i rei and G. a u t a h i in having a pair of hepatic spine on the carapace (absent in the latter two species) and the shorter distomesial spine of the antennal article 1 (far falling short of the end of the antennal article 3 in G. h a l i a, instead of reaching or overreaching it in the latter two species). Furthermore, the living color patterns of G. halia and G. autahi are different. The carapace and abdomen of G. halia is light brown, whereas the color is red in G. autahi .

The genetic divergences between G. autahi and G. halia were 17.3% (COI) and 7.4% (16S rRNA) ( Tab. 2 ). No genetic data are available for G. lemaitrei .

Distribution. Red Sea, 10– 42 m.

Figures

FIGURE 55. Galathea lemaitrei n. sp., A – D, holotype, ovigerous female, 2.9 mm, Red Sea (SMF); E-H, paratype, male, 2.5 mm, Saudi Arabia, (UF 36560). A, carapace and abdomen, dorsal view; B, thoracic sternites 3 and 4; C, left part of cephalothorax, ventral view, showing antennular and antennal peduncles, and anterior part of pterygostomian flap; D, ischium, merus and carpus of right Mxp 3, lateral view; E, right P 1, dorsal view; F, right P 2, lateral view; G, right P 3, lateral view; H, right P 4, lateral view. Scale: A, E – H = 1 mm; B – D = 0.5 mm.