Leiogalathea creusa, Rodríguez-Flores & Macpherson & Machordom, 2019

Rodríguez-Flores, Paula C., Macpherson, Enrique & Machordom, Annie, 2019, Revision of the squat lobsters of the genus Leiogalathea Baba, 1969 (Crustacea, Decapoda, Munidopsidae) with the description of 15 new species, Zootaxa 4560 (2), pp. 201-256 : 225-227

Leiogalathea creusa n. sp.

( Figs. 8 , 10H )

Type material. Holotype: French Polynesia. TARASOC Stn CP 3376, 15°41'S, 146°54'W, 646–737 m, 0 4 October 2009: 1 F 5.0 mm (MNHN-IU-2014-13716).

Etymology. From the name Creusa, Aeneas ’s wife at Troy, and the mother of Ascanius in the Aeneid. The name is considered a substantive in apposition.

Description. Carapace: 1.3 × as long as broad. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove, followed by 5 medially interrupted transverse ridges. Lateral margins straight and subparallel, with 5 strong spines: first spine anterolateral, well-developed, small spine on hepatic margin, spine on anterior branchial margin, and 2 spines on posterior branchial margin. Rostrum horizontal, dorsally flattish, 1.6 × as long as broad, length and breadth 0.3 × that of carapace; lateral margin with 4 or 5 teeth, decreasing in size distally.

Sternum: Sternite 3 subquadrangular, 2.5–3.0 × as wide as long, anterolaterally produced, anterior margin serrated, straight, with a median very shallow notch. Sternite 4 broadly contiguous to sternite 3; surface depressed in midline, smooth; greatest width 3.1 × that of sternite 3, 2.5 × as wide as long.

Abdomen: Tergites 2–3 each with 2 elevated transverse ridges, tergites 4–5 with 1 transverse ridge, tergite 6 smooth; tergite 6 with transverse posteromedian margin.

Eye: Ocular peduncle slightly longer than wide; cornea subglobular, maximum corneal diameter 0.8 × rostrum width, as wide as eyestalk.

Antennule: Article 1 with distomesial angle armed with 1 small spine; lateral margin smooth.

Antenna: Article 1 with distomesial spine not reaching end of article 2; article 2 with strong distomesial spine larger than distolateral, nearly reaching end of article 3; articles 3 and 4 unarmed.

Mxp3: Ischium as long as merus measured along extensor margin; flexor margin sharply ridged, terminating in small spine; extensor margin unarmed; crista dentata finely denticulate; merus having flexor margin with strong median spine, extensor margin with distal spine.

P1: 2.2 × carapace length, with numerous short scale-like striae, and uniramous setae scattered on merus to dactylus without stiff long setae. Merus 0.7 × as long as carapace, 1.9 × as long as carpus, with strong mesial and distal spines, and scattered dorsal spines. Carpus 0.8 as long as palm, 1.5 × as long as broad, dorsal surface with scattered spines, mesial and lateral margins with 2–3 spines. Palm, 1.5 × as long as broad, armed with spines in irregular longitudinal rows on mesial and lateral margins, dorsal surface unarmed. Fingers as long as or slightly longer than palm; fixed finger with a row of spines along lateral margin; movable finger with proximal mesial spine.

P2–4: Stout, somewhat compressed laterally, with short setiferous striae on dorsal surface, with sparse long and thick setae on ischium to dactylus. 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, 4.8 × as long as broad, 1.2 × as long as P2 propodus; P3 merus 3.7 × as long as broad, 1.1 × as long as P3 propodus; P4 merus 3.4 × as long as broad, 1.2 × as long as P4 propodus; extensor margins with row of 8–11 proximally diminishing spines on P2–3; extensor margin unarmed on P4; lateral surface unarmed; flexor margin with well-developed distal spine and several additional projecting scales. Carpi with 4 or 5 spines on extensor margin on P2–3, unarmed on P4, lateral side smooth; flexor margin with small dorsal spine. Propodi 5.0–6.7 × as long as broad on P2–4, flexor margin with 4 or 5 movable spinules along. Dactyli 0.6 × length of propodi; distal claw short, moderately curved; flexor margin often oblique, with 7 small teeth along the entire margin decreasing in size proximally, each with slender movable spinule, ultimate tooth equidistant between base of distal claw and penultimate tooth.

Colour in life. Unknown.

Genetic data. COI (no data for 16S) ( Table 2).

Distribution. French Polynesia, from 646 to 737 m.

Remarks. Leiogalathea creusa belongs to the group of species having the hepatic margin of the carapace armed with one spine. This species is morphologically related to L. anchises from Papua New Guinea and the Solomon Islands. They can be distinguished on the basis of the following traits:

The P1 is densely covered with long setae in L. anchises rather than minimally setose in L. creusa .

L. creusa has slender rostrum (1.6 × as long as broad) whereas the rostrum is 1.2–1.3 × as long as broad in L. anchises .

The genetic distance between these two species is 7.1% in COI (no data for 16S).

Figures

FIGURE 8. Leiogalathea creusa n. sp., holotype, F 5.0 mm, French Polynesia (MNHN-IU-2014-13716). A, carapace and abdomen, dorsal view. B, sternites 3–4. C, cephalic region, showing antennular and antennal peduncles, ventral view. D, right Mxp3 ischium and merus, lateral view. E, right P1, dorsal view. F, right P2, lateral view. G, dactylus of right P2, lateral view. H, right P3, lateral view. I, right P4, lateral view. Scales: A, E, F, H, I = 1.0 mm; B–D, G = 0.5 mm.

FIGURE 10. Rostrum, and ocular peduncle, dorsal view. A, Leiogalathea achates n. sp., holotype, ov. F 3.6 mm (MNHN-IU- 2016-7125). B, L. aeneas n. sp., holotype, F 7.6 mm (SMF51246). C, L. agassizii (A. Milne Edwards, 1880), F 6.9 mm (SMF51247), Florida. D, L. amata n. sp., holotype, F 3.6 mm (MNHN-IU-2014-13779). E, L. anchises n. sp., holotype, F 6.4 mm (MNHN-IU-2014-13786). F, L. ascanius n. sp., holotype, M 5.9 mm (MNHN-IU-2013-17425). G, L. camilla n. sp., holotype, M 3.0 mm, (MNHN-IU-2014-13728). H, L. creusa n. sp., holotype, F 5.0 mm (MNHN-IU-2014-13716). I, L. dido n. sp., holotype, ov. F 9.8 mm (MNHN-IU-2013-17431). Scale = 1 mm.