Leiogalathea pallas, 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: 239-242
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Leiogalathea pallas n. sp.
Leiogalathea laevirostris .— Baba 1991: 487 –488 (in part, only specimens from MUSORSTOM 4 and BIOGEOCAL).
Vanuatu. MUSORSTOM 8 Stn DW1009, 17°46'S, 168°13'E, 430–460 m, 27 September 1994 GoogleMaps : 1 M 7.1 mm, 3 ov. F 4.7–6.0 mm, 1 F 2.8 mm (MNHN-IU-2014-13761).— Stn DW1015, 17°54'S, 168°22'E, 420– 375 m GoogleMaps , 27
September 1994: 1 ov. F 4.7 mm (MNHN-IU-2014-13764).—Stn CP1049, 16°39'S, 168°03'E, 469–525 m, 1 October 1994: 1 ov. F 4.6 mm, 1 F 3.6 mm (MNHN-IU-2014-13762).—Stn DW 1060, 16°14'S, 167°21'E, 394– 375 m, 2 October 1994: 1 F 5.3 mm (MNHN-IU-2014-13763).—Stn DW 1061, 16°15'S, 167°20'E, 458–512 m, 2 October 1994: 1 F 4.8 mm (MNHN-IU-2014-13765).
Vanuatu. SANTO Stn AT 10, 15°41'S, 167°01'E, 509–659 m, 17 September 2006: 1 M 8.3 mm (MNHN-IU- 2014-13775) GoogleMaps .
Solomon Islands. BOA 1 Stn CP 2415, 15°44'S, 167°03'E, 420–670 m, 5 September 2005: 1 ov. F 6.3 mm (MNHN-IU-2014-13771) GoogleMaps .
Chesterfield Islands. EBISCO StnDW2629, 21°06'S, 160°46'E, 569–583 m, 21 October 2005: 1 M 6.0 mm (MNHN-IU-2014-13785).
Papua New Guinea. MADEEP Stn DW4268, 05°33'S, 153°59'E, 383–720 m, 27 April 2014: 1 specimen broken (MNHN-IU-2015-921).—Stn DW4274, 05°38'S, 153°56'E, 435–442 m, 27 April 2014: 1 M 7.8 mm (MNHN-IU-2015-912) GoogleMaps .
Etymology. From the name Pallas, son of the King Evander in the Aeneid. The name is considered a substantive in apposition.
Description. Carapace: 1.2–1.3 × as long as broad. Mid-transverse ridge usually interrupted, preceded by deep cervical groove, followed by 6 or 7 interrupted transverse ridges. Lateral margins convex, with 4 spines: first spine anterolateral, well-developed; hepatic margin unarmed; 2 spines on anterior branchial margin variable in size (posterior spine smaller, rarely obsolescent), and spine on posterior branchial margin. Rostrum horizontal, dorsally flattish or slightly concave, 1.7–1.9 × as long as broad, length 0.3 × and breadth 0.2–0.3 × that of carapace; lateral margin minutely serrated.
Sternum: Sternite 3 moderately broad, 3.2–3.7 × as wide as long, anterolaterally strongly produced, anterior margin with shallow median notch flanked by 2 lobes. Sternite 4 narrowly contiguous to sternite 3; surface depressed in midline, smooth; greatest width 4.4 × that of sternite 3, and twice as wide as long.
Abdomen: Tergites 2–3 each with 2 elevated transverse ridges, tergite 4 with transverse ridge, tergites 5–6 smooth; tergite 6 with transverse posteromedian margin.
Eye: Ocular peduncle slightly longer than wide; cornea subglobular, maximum corneal diameter 0.8 × rostrum width, as wide as eyestalk.
Antennule: Article 1 with distomesial angle serrated; lateral margin serrated.
Antenna: Article 1 with strong distomesial spine overreaching end of article 2; article 2 with strong distomesial spine larger than distolateral spine and reaching or overreaching 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 well-developed spine; extensor margin unarmed; crista dentata finely denticulate; merus having flexor margin with strong median spine, extensor margin with well-developed distal spine.
P1: 2.5–3.5 (male), 2.2–2.7 (female) × carapace length, with numerous short striae, and covered by scales with uniramous long and short setae on merus to dactylus. Merus as long as carapace, 2.5 × as long as carpus, with strong mesial and distal spines, and scattered dorsal spines. Carpus 0.6 shorter than palm, 1.4 × as long as broad, dorsal surface with scattered spines, mesial and lateral margins with 2 – 4 strong spines. Palm, 1.7 × as long as broad, armed with spines in irregular longitudinal rows on mesial and lateral margins, dorsal surface unarmed. Fingers as long as palm; fixed finger with row of spines along lateral margin; movable finger with well-developed proximal mesial spine.
P2–4: Slender, somewhat compressed laterally, with short setiferous striae on dorsal surface, with numerous long and thick setae on ischium to dactylus. Meri successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.7–0.8 × length of P3 merus). P2 merus 0.9 × carapace length, 8 × as long as broad, 1.2 × as long as P2 propodus; P3 merus 5.3 × as long as broad, 1.2 × as long as P3 propodus, P4 merus 4.2 × as long as broad, 1.3 × as long as P3 propodus; extensor margins with a row of 8–11 proximally diminishing spines on P2–4; 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 P2–4, smooth lateral side; flexor margin with small distal spine. Propodi 11.0–11.6 × as long as broad on P2–3, 8 × as long as broad on P4, flexor margin with 3–5 movable spinules. Dactyli slender, 0.5 × length of propodi; distal claw short, moderately curved; flexor margin nearly straight, with 7 or 8 small teeth along entire margin decreasing in size proximally, each with slender movable spinule, ultimate tooth closer to penultimate tooth than to base of distal claw.
Colour in life. Base colour reddish, orange to pale orange. Carapace and anterior half of abdomen reddish orange, posterior part of abdomen pale orange, occasionally translucent. P1 totally reddish orange, tip of spines on mesial margin white. P2–4 reddish orange, white at basis and at tips of dactyli.
Genetic data. COI and 16S ( Table 2).
Distribution. New Caledonia, Vanuatu, Chesterfield Islands, Papua New Guinea, and Solomon Islands, from 163 to 720 m.
Remarks. Leiogalathea pallas belongs to the group of species having the hepatic margin of the carapace unarmed and the anterior branchial margin with 2 spines at most. This species is morphologically very similar to L. sinon from Tonga and Polynesia (see below, under the Remarks of that species).
Genetically, the closest species is L. amata from Wallis and Futuna and New Caledonia (genetic distance for COI and 16S: 4.1 and 1.4%, respectively) ( Table 2). However, L. pallas is clearly distinguished from L. amata by the following characters: the rostral lateral margin is serrated instead of smooth and entire; the branchial margin of the carapace has 2 or 3 instead of 1 spine; the mesial spine on the antennal article 1 clearly overreaches instead of falling short of article 2; and the flexor margin of the P2–4 dactyli has 8 instead of 5 or 6 teeth.
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