Galathea minima, 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 : 195-196

Galathea minima n. sp.

( Figs 70 , 118 D, E)

Material examined. Holotype: Papua New Guinea. PAPUA NIUGINI, Stn PD19, 05°05.4'S, 145°48.5'E, 3–10 m, 13 November 2012: ov. F 2.4 mm (MNHN-IU-2013-15980).

Paratypes: Papua New Guinea. PAPUA NIUGINI, Stn PD19, 05°05.4'S, 145°48.5'E, 3–10 m, 13 November 2012: 2 M 2.1–2.4 mm, 6 ov. F 2.2–2.8 mm (MNHN-IU-2013-704).—Stn PD31, 05°05.3'S, 145°48.1'E, 1–6 m, 12–13 December 2012: 1 ov. F 2.4 mm (MNHN-IU-2013-9760).— Stn PS15, 05°05.79'S, 145°48.194'E, 12 m, 30 December 2012: 1 M 2.2 mm, 1 ov. F 2.5 mm (MNHN-IU-2013-9759).—Stn PB19, 05°05.1'S, 145°48.6'E, 10 m, 30 December 2012: 1 ov. F 2.5 mm (MNHN-IU-2013-654).

Etymology. From the Latin minimus, very small, in reference to the small size of the species.

Description. Carapace: As long as broad; anterior cervical groove indistinct; ridges with dense short setae, a few median long iridescent setae on protogastric ridge. Gastric region with some transverse ridges: 1 epigastric ridge, medially interrupted, with 2 small spines, absent in some individuals; 1 protogastric ridge, medially convex, uninterrupted, extending laterally to carapace margin, without parahepatic spines; 1 mesogastric ridge uninterrupted and not extending (extending in a few specimens) laterally to first branchial spine; 2 metagastric ridges, anterior ridge uninterrupted, continuing laterally to anteriorbranchial ridge, posterior ridge short. Midtransverse ridge uninterrupted, preceded by shallow cervical groove. Posterior branchial region with 5 transverse ridges, 2 or 3 ridges uninterrupted. Lateral margins medially convex, with 6 or 7 spines: 1 spine in front of and 5 or 6 spines behind indistinct anterior cervical groove; first anterolateral, well-developed, at same level of lateral limit of orbit, accompanying another spine ventral to between first and cervical groove; 3 spines on anterior branchial region, last small, and 2 or 3 spines on posterior branchial margin, last small. External limit of orbit ending in small spine; infra-orbital margin with strong spine. Rostrum broad triangular, 1.1 times as long as broad, length 0.6 that of, breadth 0.4–0.5 that of carapace; distance between distalmost lateral incisions 0.20–0.25 distance between proximalmost lateral incisions, dorsal surface nearly horizontal in lateral view, with few scales; lateral margin with 4 sharp teeth.

Pterygostomian flap rugose, with spine on anterior ridge, anterior margin ending in well-developed spine.

Sternum: Slightly broader than long, lateral limits divergent posteriorly.

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

Eyes: Ocular peduncles as long as broad, maximum corneal diameter 0.7 rostrum width.

Antennule: Article 1 with 3 well-developed distal spines, distomesial clearly smaller than others. Ultimate article with long tuft of setae on distodorsal margin.

Antenna: Article 1 with depressed ventral distomesial process reaching distal margin of article 2. Article 2 with distomesial spine longer than or as long as distolateral, exceeding midlength of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with well-developed distal spine on flexor margin; extensor margin unarmed; crista dentata with 17 or 18 denticles. Merus shorter than ischium, with 2 spines on flexor margin, proximal one located at midlength, slightly longer than or as long as distal spine; extensor margin with small distal spine. Carpus unarmed.

P1: 1.8–1.9 times carapace length, with numerous short setae and some scattered long plumose setae. Merus 0.6–0.7 times carapace length, 1.2–1.3 times as long as carpus, with rows of spines, mesial and distal spines strong. Carpus 1.1–1.3 length of palm, 2.1–2.2 times longer than broad, lateral and mesial margins subparallel, dorsal surface with some small spines; mesial surface with row of spines, with one strong spine; and row of small spines along lateral margin. Palm 1.6–1.7 times longer than broad, lateral and mesial margins subparallel and with row of spines; small spines roughly in rows on dorsal side; lateral row continued on to lateral margin of fixed finger; mesial row not continuing on the mesial margin of movable finger. Fingers 1.1–1.2 times palm length, each finger distally with two rows of teeth, spooned.

P2–4: Relatively slender, moderately setose, sparsely with long setae on all articles. P2 1.6–1.8 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P2 merus, P4 merus 0.8 length of P3 merus); P2 merus 0.6–0.7 carapace length, 3.1–3.4 times as long as broad, 1.4–1.5 times longer than P2 propodus; P3 merus 3.0 times as long as broad, 1.2–1.3 times length of P3 propodus; P4 merus 2.8–3.1 times as long as broad, 1.1–1.3 length of P4 propodus. Extensor margin of merus with row of 8 or 9 proximally diminishing spines on P2–3, unarmed on P4; flexolateral surface unarmed on P2–3, 1 or 2 minute spines on P4, margins with strong terminal spine and 1 or 2 additional spines on terminal half; flexomesial margins unarmed. Carpi with 4 or 5 spines on extensor margin on P2–3, 0–1 spines on P4; lateral surface with row of 2–4 small spines or acute granules paralleling extensor row; flexor distal margins with spine. Propodi 4 times as long as broad; extensor margin unarmed; flexor margin with 3 or 4 slender movable spines. Dactyli subequal in length, 0.6 length of propodi, ending in incurved, strong, sharp spine; flexor margin with prominent triangular terminal tooth preceded by 4 obsolescent teeth.

Epipods present on P1–3.

Coloration. Variable color pattern. Ground color orange or greenish. Rostrum whitish. Some whitish flecks on carapace and abdomen of greenish specimens. P1–4 translucent whitish, with some reddish diffuse bands.

Remarks. Galathea minima n. sp. resembles G. rubrispina n. sp. from Papua New Guinea (see Remarks for the latter species).

No genetic data are available for G. minima .

Distribution. Papua New Guinea, 3– 13 m.

Figures

FIGURE 70. Galathea minima n. sp., holotype, ovigerous female, 2.4 mm, Papua New Guinea (MNHN-IU- 2013 - 15980). 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).