Leiogalathea evander Rodríguez-Flores & Macpherson & Machordom 2019, n. sp.
Creators: name: Rodríguez-Flores, Paula C.
name: Macpherson, Enrique
name: Machordom, Annie
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Galatheidae
Leiogalathea
Leiogalathea evander

description: Leiogalathea evander n. sp.
(Figs. 11A, 12, 21C)
Type material. Holotype: Papua New Guinea. MADEEP Stn DW4288, 09°12'S, 153°54'E, 504 m, 30 April 2014: 1 M 3.9 mm (MNHN-IU-2015-820).
Paratypes: Marquesas Islands, Polynesia. MUSORSTOM 9 Stn DR 1253, 9°47.9'S, 139°38.1'W, 360–405 m, 2 September 1997: 1 M 4.8 mm (MNHN-IU-2013-17420).— Stn DR 1255, 9°38.5'S, 139°48.4'W, 416–440 m, 2 September 1997: 1 ov. F 4.0 mm (MNHN-IU-2013-17429).— Stn CP 1282, 7°51.7'S, 140°30.6'W, 416–460 m, 7 September 1997: M 4.9 mm (MNHN-IU-2013-17421).— Stn CP 1306, 8°55.2'S, 140°14.8'W, 283–448 m, 10 September 1997: 1 M 3.7 mm (MNHN-IU-2013-17422).
Papua New Guinea. MADEEP Stn DW4286, 09°12'S, 153°55'E, 306–365 m, 30 April 2014: 2 M 4.8–5.9 mm, 1 ov. F 3.8 mm (MNHN-IU-2015-146, MNHN-IU-2016-9657).
Etymology. From the name Evander, king of Pallanteum and father of Pallas in the Aeneid. The name is considered a substantive in apposition.
Description. Carapace: 1.1–1.3 × as long as broad. Mid-transverse ridge usually medially interrupted or scalelike, preceded by shallow cervical groove, followed by 4 or 5 laterally interrupted transverse ridges. Lateral margins slightly convex, with 2 spines: first spine anterolateral, well-developed; second spine well-developed located on anterior branchial margin, hepatic and posterior branchial margin unarmed. Rostrum slender, dorsally slightly concave and usually directed downwards, 1.6 × as long as broad, length 0.4 × and breadth 0.2–0.3 × that of carapace; lateral margin armed with 4–6 rudimentary teeth along entire margin.
Sternum: Sternite 3 moderately broad, 2.6–2.8 × as wide as long, anterolaterally produced, anterior margin minutely serrated with median notch flanked by 2 shallow lobes. Sternite 4 broadly contiguous to sternite 3; surface depressed in midline, smooth; greatest width 3 × that of sternite 3, 2.5 × as wide as long.
Abdomen: Tergites 2–3 with 2 elevated transverse ridges, tergite 4 with 1 transverse ridge, tergites 5–6 smooth; tergite 6 with transverse posteromedian margin.
Eye: Ocular peduncle slightly longer than wide; cornea subglobular, maximum corneal diameter 0.7 × rostrum width, as wide as eyestalk.
Antennule: Article 1 with distomesial angle unarmed; lateral margin smooth.
Antenna: Article 1 with short, stout distomesial spine not reaching mid-length of article 2; article 2 with distomesial spine longer than distolateral spine, not 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 1 strong median spine, extensor margin with distal spine.
P1: 2.4–2.9 (males), 1.8–2.3 (females) × carapace length, with numerous short striae, and covered by uniramous short setae on merus to dactylus, long stiff setae absent. Merus 0.7 length of carapace, 2.1 × as long as carpus, with strong mesial and distal spines, and scattered dorsal spines. Carpus slightly shorter than palm, 1.6 × as long as broad, dorsal surface with scattered spines, mesial margins with 1 or 2 strong spines, lateral margin unarmed. Palm 2.1 × as long as broad, armed with spines in irregular longitudinal rows along mesial and lateral margins, dorsal surface unarmed. Fingers 1.3 × as long as palm; fixed finger with one or several proximal spines along lateral margin; movable finger usually with 1 well-developed proximal mesial spine.
P2–4: stout, somewhat compressed laterally, with short setiferous striae on dorsal surface, with some long and thick setae on ischium to dactylus, meri successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.8 × length of P3 merus). P2 merus, 0.6 × carapace length, 4.4 × as long as broad, 1.2 × as long as P2 propodus; P3 merus 4.2 × as long as broad, 1.2 × as long as P3 propodus; P4 merus 3.7 × as long as broad, as long as P4 propodus; extensor margins with row of 7 or 8 proximally diminishing spines on P2–3; extensor margin unarmed on P4; lateral surface unarmed; flexor distal margin with well-developed distal spine and several additional projecting scales. Carpi with 2–4 spines on extensor margin on P2–3, unarmed on P4, lateral side smooth; flexor margin with small distal spine. Propodi 5.9–6.1 × as long as broad on P2–4, flexor margin with 3–5 movable spinules. Dactyli 0.6–0.7 × length of propodi; distal claw short, moderately curved; flexor margin nearly straight, with 6–8 small teeth along entire margin decreasing in size proximally, each with slender movable spinule, ultimate tooth closer to base of distal claw than to penultimate tooth.
Colour in life. Unknown.
Genetic data. COI and 16S (Table 2).
Distribution. Marquesas Island, Polynesia, Philippines and Papua New Guinea, from 283 to 504 m.
Remarks. Leiogalathea evander belongs to the group of species having the hepatic margin unarmed and is easily distinguished from all the other species by having the rostrum slender and usually inclined downwards. Male P1 fingers clearly gap in specimens reaching big sizes, although this is a character highly variable not considered in the diagnosis of the species. This species is morphologically related to L. achates from Mayotte-Glorieuses islands and Madagascar in the Western Indian Ocean. Genetic distances between these species for the molecular markers analysed are 4.4% for COI and 0.8% for 16S. However, L. evander is easily distinguished from L. achates by the following morphological characters: the rostrum is usually deflected ventrally rather than horizontal and proportionally narrower (1.6 versus 1.4–1.5 × as long as broad).
Leiogalathea evander also resembles L. camilla from New Caledonia and adjacent waters, from which it can be differentiated by the rostrum usually deflected ventrally instead of straight horizontal or directed slightly downwards, and its lateral margin with rudimentary or obsolete instead of sharp teeth. Their genetic distance is high: 13.6% for COI and 6.7% for 16S.
description: Published as part of 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, pp. 201-256 in Zootaxa 4560 (2) on pages 230-233, DOI: 10.11646/zootaxa.4560.2.1, http://zenodo.org/record/2627514