Eumunida turbulenta, Macpherson & Rodríguez-Flores & Machordom, 2020

Macpherson, Enrique, Rodríguez-Flores, Paula C. & Machordom, Annie, 2020, New occurrences of squat lobsters of the genus Eumunida Smith, 1883 (Decapoda Eumunididae) in New Caledonia, the Solomon Islands and Papua-New Guinea with the description of a new species, Zootaxa 4786 (4), pp. 485-496 : 492-494

Eumunida turbulenta n. sp.

( Figs. 2 A–E, H, 3)

Eumunida aff. annulosa .— Puillandre et al. 2011: 330, fig. 2 (molecular data).

Type material. Holotype.— Chesterfield Islands . KANADEEP Stn DW 5012, 22°07’S, 159°19’E, 330–920 m, 19.9.2017: F ov. 16.0 mm (MNHN-IU-2014-23780).

Paratypes.— New Caledonia. NORFOLK 1 Stn DW 1700, 24°40’S, 168°40’E, 572–605 m, 24.6.2001: 4 M 5.4–8.5 mm (MNHN-IU-2014-21168 to 21171).—NORFOLK 2 Stn DW 2067, 25°16.46’S, 168°55.76’E, 614–690 m, 26.10.2003: 1 M 11.0 mm (MNHN-IU-2014-21172).— Stn DW 2077, 25°20.63’S, 168°18.53’E, 666–1000 m, 27.10.2003: 1 M 4.9 mm (MNHN-IU-2014-21173).— Stn DW 2091, 24°45.36’S, 168°06.24’E, 600–896 m, 29.10.2003: 3 M 8.8–9.6 mm (MNHN-IU-2014-21174 to 21176).—KANOCONO Stn DR 4771, 23°03’S, 168°20’E, 220–900 m, 28.8.2016: 1 ov. F 12.6 mm (MNHN-IU-2014-23786) .

Chesterfield Islands . KANADEEP Stn DW 4962, 23°02’S, 159°28’E, 315–1260 m, 6.9.2017: 2 M 4.7–11.5 mm, 1 ov. F 15.6 mm, 3 F 4.8–9.1mm (MNHN-IU-2014-23777).— Stn CP 4992, 24°14’S, 166°58’E, 490–855 m, 13.9.2017: 1 M 5.8 mm (MNHN-IU-2017-10545).— Stn DW 5012, 22°07’S, 159°19’E, 330–920 m, 19.9.2017: 2 M 9.0– 10.1 mm, 2 F 6.8–8.4 mm (MNHN-IU-2016-9635) .

Etymology. From the Latin, turbulentus, confused, in relation with the taxonomic confusion of the new species.

Description. Carapace: As long as broad, exclusive of rostrum. Gastric region well defined, moderately convex; 3 hepatic spines, first (anteriormost) spine strong, near base of lateral supraocular spine, second and third spines small and subequal in size. Cervical groove and its posterior branch distinctly marked,separating cardiac and branchial areas. Transverse ridges with short dense setae; anterior branchial region with few short squamiform striae; six transverse ridges behind cervical groove, first and second interrupted in cardiac region; third to sixth usually complete. Lateral margins convex, armed with 6 spines decreasing in size posteriorly, 2 anterolateral spines anterior to posterior cervical groove; first spine less than half length of lateral supraocular spine, and not reaching sinus between supraocular spines, slightly longer than second anterolateral spine. Greatest width measured between fifth and sixth lateral spines. Rostrum sharply spiniform, deflected slightly ventrally, nearly one-half of remaining carapace; mesial supraocular spine terminating in distal one-third of rostral spine, longer than lateral supraocular. Pterygostomian flap anteriorly produced to strong spine.

Sternal plastron: Slightly longer than broad, medially concave; pair of well-developed median processes on anterior margin of sternite 3. Sternite 4 with prominent lateral spine on each side, surface with several short striae. Lateral sides successively divergent posteriorly between sternites 4–7.

Abdomen: Tergites 2–3 with 3 transverse ridges and few short striae on each side and between second and third ridges. Tergites 4–5 with obsolescent ridges. Telson with posterior margin emarginate medially.

Eye: Short, corneae moderately dilated, breadth 0.7 times distance between hiatuses formed by outer and inner supraocular spines, slightly exceeding end of lateral supraocular spine.

Antenna: Article 1 with short distolateral spine. Article 2 with strong distolateral spine nearly reaching midlength of article 4. Acicle spiniform, slender, reaching base of article 5. Article 3 with long distal spine, slightly exceeding distal margin of article 4. Article 4 3.5–3.7 times longer than broad, with strong distomesial spine reaching distal margin of antennal peduncle; distolateral angle unarmed. Article 5 with 3 distal spines (dorsal, mesial and lateral), lateral spine largest.

Mxp3: Merus with small median spine on flexor margin; ischium crista dentata of 10–12 denticles.

P1: 4.1–4.6 pcl. Ischium with moderate-sized ventral spine; merus squamate, 1.7–1.9 pcl, armed with 3 rows of spines (dorsolateral, dorsal, and dorsomesial); dorsomesial row composed of large and small spines regularly alternated; few ventral small spines. Carpus squamate, with 3 distal spines. Palm 1.2–1.3 times length of fingers, moderately massive, with sparse short setae and few uniramous long setae, mesially with 3-5 spines in 2 rows (dorsomesial and ventromesial); with setal pad distally on ventral surface. Fingers not gapping, furnished with relatively long coarse setae; opposable margins as illustrated.

P2-4: Squamate, sparsely furnished with long coarse setae. P2 merus slightly shorter than carapace, 1.1–1.2 times longer than propodus, with well-developed extensor spines, proximal few small and one strong disto-flexor spine; carpus with several acute spines on extensor margin, distalmost largest; propodus nearly smooth on extensor margin, armed with 8–10 spinules along flexor margin; dactylus about one-third as long as propodus, with 9–10 movable spinules, along extensor border. P3 similar to P2, but merus slightly shorter. P4 merus 0.7–0.8 times length of P2 merus, armed with row of spines along midline of extensor-lateral face.

Genetic data. COI (GenBank Accession numbers EU243360 , EU243472 , EU243506 , EU243353 , EU243506 ), 28S (GenBank Accession numbers EU243577 , EU243625 , EU243583 ) (see Puillandre et al. 2011, Table 1 as E. annulosa ) .

Distribution. New Caledonia, Norfolk Ridge, and Chesterfield Islands; between 220 and 1260 m.

Remarks. In their genetic study on 30 species of the genus Eumunida, Puillandre et al (2011) , suggested the existence of this new species provisionally identified as E. aff. annulosa (see above the differences under the Remarks of E. annulosa ), as a sister taxa of E. sternomaculata de Saint-Laurent & Macpherson, 1990 , and E. treguieri de Saint-Laurent & Poupin, 1996 . The new species, E. turbulenta , morphologically belongs to the group of species which possess two well-developed spines in the anterior border of sternite 4 (subgenus Eumunida de Saint-Laurent & Poupin 1996 ), complete striae on the posterior region of the carapace, two anterolateral spines of the carapace (anterior to the posterior cervical groove), a ventral pad on the P1 palm and three distal spines on the P1 carpus. This group includes two other species: E. australis de Saint-Laurent & Macpherson, 1990 , from northern Australia to Tasman Sea and E. sternomaculata . However, the new species is readily distinguishable from these species by the following aspects (for the morphology of the latter two species, see de Saint-Laurent & Macpherson 1990a, b):

- The size of the anterolateral (first lateral) spine of the carapace is less than half instead of two-thirds the length of the lateral supraocular spine.

- The antennal article 2 has the distolateral spine longer, nearly reaching instead of never reaching the midlength of article 4; the antennal article 4 is more than 3.5 instead of less than 2.5 times longer than broad, with the distolateral angle unarmed instead of bearing a well-developed spine ( Figs. 2E, G ).

Eumunida treguieri is easily differentiated from the new species by the presence of three instead of two anterolateral spines on the carapace.

Genetically, the new species is different from E. sternomaculata , with genetic distances for COI and 28S: 5.2– 6.4% and 4.7–4.8%, respectively, and is also from E. treguieri , with genetic distances for COI and 28S: 4.4–5.2% and 5.0%, respectively ( Puillandre et al. 2011).

Figures

FIGURE 2. Eumunida turbulenta n. sp., A–E, H, holotype, ov. F 16.0 mm, Chesterfield Islands (MNHN-IU-2014-23780); F, E. annulosa, F 16.0 mm, New Caledonia (MNHN-IU-2014-23761); G, E. sternomaculata, F 14.7 mm, New Caledonia (MNHN- IU-2011-4533). A, carapace and abdomen, dorsal. B, carapace, right side, lateral. C, sternal plastron. D, telson. E–G, left antenna, ventral. H, right Mxp3 ischium to carpus, lateral. Scale: A–D = 2.0 mm; E–H = 1.0 mm.