Galathea gnoma Macpherson & Robainas-Barcia, 2015, n. sp.
Creators: name: Macpherson, Enrique
name: Robainas-Barcia, Aymee
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Galatheidae
Galathea
Galathea gnoma

description: Galathea gnoma n. sp.   
(Fig. 43)  
 Material examined. Holotype: Indonesia. Kei Islands. KARUBAR, Stn DW30, 05°39'S, 132°56'E, 111–118 m, 26 October 1991: M 2.7 mm (MNHN-IU-2013-13513).   
 Paratypes: Vanuatu. MUSORSTOM 8, Stn CP1131, 17°52.95'S, 168°33.11'E, 140–175 m, 29 September 1994: 1 M 3.5 mm (MNHN-IU-2013-13952); 1 ov. F 3.2 mm (MNHN-IU-2013-13953). SANTO, Stn EP36, 15°33.1–33.3'S, 167°12.4–12.7'E, 20–60 m, 15 October 2006: 2 M 2.4–2.6 mm, 2 F 2.4–2.5 mm (MNHN-IU- 2013-13985).   
 Etymology. From the Latin gnomus, dwarf, in reference to the small size of the species.   
 Description. Carapace: Slightly longer than broad; transverse ridges with dense short setae, with scattered long non-iridescent setae; cervical groove distinct, laterally bifurcated. Gastric region with 5 transverse ridges: 1 epigastric ridge medially interrupted, with 2 spines; 2 protogastric ridges, anterior ridge medially interrupted (uninterrupted in paratypes), with posterior median arcuate scale-like ridge, and 1 small parahepatic spine on each side; 1 mesogastric ridge medially uninterrupted or medially interrupted, not continuing laterally with anteriormost branchial spines; 2 metagastric ridges, anterior ridge uninterrupted, not continuing laterally to anterior branchial ridges, posterior one short. Anterior branchial region with distinct ridges. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove, followed by 4 ridges, 1 or 2 of them uninterrupted. Lateral margins slightly convex, with 6 spines: 2 spines in front of and 4 spines behind anterior cervical groove; first anterolateral, welldeveloped, at same level of lateral limit of orbit, second very small, with spine ventral to between first and second spines; 2 spines on anterior branchial region, and 2 spines on posterior branchial margin. Lateral limit of orbit with small spine; infraorbital margin with strong spine. Rostrum narrowly triangular, 1.9–2.0 as long as broad, length 0.7 carapace length and breadth 0.4 that of carapace; distance between distalmost lateral incisions 0.25 distance between proximalmost lateral incisions; dorsal surface nearly horizontal in lateral view, with some short setae; 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: Somites 2–3 with 2 transverse uninterrupted ridges; somite 4 with anterior ridge only; somites 5–6 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 reaching distal margin of article 2. Article 2 with distolateral spine longer than distomesial, reaching midlength of article 3. Article 3 with small distomesial spine. Article 4 unarmed.   
 Mxp3: Ischium with small spine on flexor distal margin, extensor margin ending in acute point; crista dentata with 19 denticles. Merus as long as ischium; flexor margin with 2 subequal well-developed spines; extensor margin with distinct spine. Carpus unarmed.   
 P1: 3.1 times carapace length, with numerous finely setiferous scales, and some scattered long setae; setae non-iridescent. Merus 1.2 times length of carapace, 1.9 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, twice longer than broad; dorsal surfaces with a few spines; mesial margin with some well-developed spines. Palm twice longer than broad, lateral and mesial margins subparallel; spines arranged roughly in dorsolateral and dorsomesial rows. Fingers unarmed, as long as palm, 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 0.8 length of P2 merus, P4 merus 0.9 length of P3 merus); P2 merus 0.7 carapace length, 3.8 times as long as broad, 1.3 times longer than P2 propodus; P3 merus 2.8 times longer than broad, slightly longer than P3 propodus; P4 merus 2.7 times as long as broad, slightly longer than P4 propodus. Extensor margins of meri with row of 7 or 8 proximally diminishing spines on P2–3, 6 spines on P4; flexor margins distally ending in strong spine followed proximally by several tubercles or eminences; lateral sides unarmed. Carpi with 6 or 7 spines on extensor margin, distalmost smaller than distal second; lateral surface with 2 or 3 granules sub-paralleling extensor margin on P2–4; flexor margin blunty produced. Propodi 3.5–4.0 times as long as broad; extensor margin with 3 or 4 small proximal spines on P2–4; flexor margin with 5 or 6 slender movable spines on P2–4. Dactyli distally ending in well-curved strong spine, length 0.7–0.8 that of propodi; flexor margin with 5 proximally diminishing teeth, terminal one prominent.   
Epipods only on P1.  
 Remarks. Galathea gnoma n. sp. is most closely related to G. denticulata Macpherson & Cleva. 2010 from Mayotte Island. The two species can be distinguished by the following characters:   
 - The rostral lateral tooth are shallowly incised in G. denticulata, but deeply incised in G. gnoma. - The carapace has one hepatic spine on each side but parahepatic spines are absent in G. denticulata, whereas the hepatic spines are absent but the parahepatic spines are present in G. gnoma.   
 The new species is also close to G. p a r v u l a (see under Remarks of this latter species).   
 No genetic data for G. gnoma are available.   
 Distribution. Indonesia (Kei Islands), Vanuatu; 20– 175 m.
description: Published as part of 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, pp. 1-335 in Zootaxa 3913 (1) on pages 128-130, DOI: 10.11646/zootaxa.3913.1.1, http://zenodo.org/record/239230