Galathea parvula, 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 : 209-212

Galathea parvula n. sp.

( Figs 75 , 118 G)

Material examined. Holotype: Saudi Arabia, Yanbu, 24.4427°N, 37.2477'E, 3–22 m, 4 October 2013: ov F 2.9 mm (UF38286).

Etymology. From the Latin parvulus, child, in reference to the small size of the species. Description. Carapace: Slightly longer than broad; transverse ridges with short setae, with scattered long nonplumose, iridescent setae; cervical groove distinct, laterally bifurcated. Gastric region with 5 transverse ridges: 1 epigastric ridge medially interrupted, with 2 spines; 1 protogastric ridge, uninterrupted (medially interrupted in one paratype), 1 parahepatic spine on each side between epigastric and protogastric ridges; 1 mesogastric ridge, scalelike, not continuing laterally with anteriormost branchial spines; 2 metagastric ridges, anterior ridge medially interrupted, not continuing laterally to anterior branchial ridges, posterior one short. Anterior branchial region with some ridges. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove, followed by 4 ridges, 2 of them uninterrupted. Lateral margins slightly convex, with 7 spines: 2 spines in front of, and 5 spines behind, anterior cervical groove; first anterolateral, well-developed, behind level of lateral limit of orbit, second small, with spine ventral to between first and second spines; 2 spines on anterior branchial region, and 3 spines on posterior branchial margin. Lateral limit of orbit with small spine; infraorbital margin with strong spine. Rostrum narrowly triangular, 1.7 as long as broad, length 0.6 carapace length and breadth 0.4 that of carapace; distance between distalmost lateral incisions 0.25 distance between proximalmost lateral incisions; dorsal surface slightly concave; lateral margin with 4 deeply incised sharp teeth.

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

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

Abdomen: Somite 2 with 2 transverse uninterrupted ridges; somite 3 with 1 anterior uninterrupted ridge and 1 scale-like ridge; somites 4-6 smooth; posteromedian margin of somite 6 straight. Males with G1 and G2.

Eyes: Ocular peduncles 1.5 times longer than broad, maximum corneal diameter 0.7 rostrum width.

Antennule: Article 1 with 3 well-developed distal spines, distodorsal larger than others. Ultimate article with a few short fine setae not in tuft on distodorsal margin.

Antenna: Article 1 with ventral distomesial spine exceeding distal margin of article 3. Article 2 with subequal distolateral and distomesial spines, reaching midlength of article 3. Article 3 with minute distomesial spine. Article 4 unarmed.

Mxp3: Ischium with small spine on flexor distal margin, extensor margin ending in acute point; crista dentata with 22–25 denticles. Merus as long as ischium; flexor margin with 2 spines, proximal longer than distal; extensor margin with small distal spine. Carpus unarmed.

P1: 2.5–3.0 times carapace length, with some finely setiferous scales, and some scattered long setae; some setae iridescent. Merus 0.9–1.2 times length of carapace, 1.5 times as long as carpus, with spines arranged roughly in rows, dorsomesial spines stronger; distal spines prominent. Carpus 0.8–1.0 length of palm, 2.0–2.2 times longer than broad; dorsal surfaces with a few minute spines; mesial margin with 1 strong median spine and some additional smaller spines. Palm 2.4 times longer than broad, lateral and mesial margins subparallel; spines arranged roughly in dorsolateral and dorsomesial rows; dorsolateral row continuing along fixed finger; some scattered small dorsal spines. Fingers as long as palm, movable finger unarmed; each finger with two rows of teeth distally spooned.

P2–4: Moderately long and slender, with setose striae and long setae; setae non-iridescent. P2 1.8 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P2 merus, P4 merus 0.9 length of P3 merus); P2 merus 0.7 carapace length, 4.5 times as long as broad, 1.5 times longer than P2 propodus; P3 merus 3.5 times longer than broad, 1.3 times longer than P2 propodus; P4 merus 3.5 times as long as broad, slightly longer than P4 propodus. Extensor margins of meri with row of 8 or 9 proximally diminishing spines on P2–3, 2 or 3 spines on P4; flexor margins distally ending in strong spine followed proximally by several tubercles or eminences; lateral sides unarmed. Carpi with 3 or 4 spines on extensor margin; lateral surface with 2 or 3 granules subparalleling extensor margin on P2–4; flexor margin blunty produced. Propodi 4.2–4.6 times as long as broad; extensor margin with 1 or 2 small proximal spines on P2–4; flexor margin with 4 or 5 slender movable spines on P2–4. Dactyli distally ending in well-curved strong spine, length 0.6–0.7 that of propodi; flexor margin with 5 proximally diminishing teeth, terminal one prominent.

Epipods on P1–2.

Coloration. Base color of carapace and abdomen reddish. P1 with transverse reddish and whitish stripes. P2–4 with distal part of meri, carpi and propodi with darker red transverse ridges. Rostrum and eyes peduncle reddish.

Remarks. Galathea parvula is closely related to G. gnoma n. sp. from Indonesia and Vanuatu. The two species can be distinguished by the following characters:

- Epipods are present on P 1–2 in G. parvula , instead of P1 only in G. gnoma .

- The protogastric region has one median arcuate scale-like ridge posterior to anterior protogastric ridge in G. gnoma , whereas this scale-like ridge is absent in G. parvula .

- The lateral margin of the fixed finger of P1 has a row of spine in the present new species, whereas this margin is unarmed in G. gnoma .

- The mesial margin of P1 carpus has one strong median spine in the new species, that is absent in G. gnoma .

- The distomesial spine of antennal article 1 slightly exceeds article 2 in G. gnoma , whereas this spine exceeds article 3 in G. parvula .

- The two spines on the flexor margin of Mxp3 merus are subequal in G. gnoma , whereas the proximal is clearly longer than distal spine in the new species.

No genetic data are available for G. parvula .

Distribution. Red Sea, Saudi Arabia, 3– 22 m.

Figures

FIGURE 75. Galathea parvula n. sp., holotype, ovigerous female, 2.9 mm, Saudi Arabia (UF 38286). 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.

FIGURE 118. Dorsal view. A, Galathea maculiabdominalis Baba, 1972, Vanuatu, male 2.4 mm (MNHN-IU- 2013 - 8344). B, Galathea mariae n. sp., French Polynesia, ovigerous female 3.0 mm (UF 15523). C, Galathea mauritiana Bouvier, 1914, Madagascar, female 2.5 mm (IU- 2013 - 9740). D, Galathea minima n. sp., Papua New Guinea, ovigerous female 2.8 mm (MNHN-IU- 2013 - 704). E, Galathea minima n. sp., Papua New Guinea, ovigerous female 2.5 mm (MNHN-IU- 2013 - 654). F, Galathea ohshimai Miyake & Baba, 1967, Vanuatu, male 2.2 mm (MNHN-IU- 2013 - 13881). G, Galathea parvula n. sp., holotype, ovigerous female 2.9 mm (UF 38286). H, Galathea paulayi n. sp., French Polynesia, male 4.7 mm (UF 15618). I, Galathea peitho n. sp., Papua New Guinea, male 4.0 mm (MNHN-IU- 2013 - 372).