Typhlonida eluminata, Macpherson & Rodríguez-Flores & Machordom, 2024

Macpherson, Enrique, Rodriguez-Flores, Paula C. & Machordom, Annie, 2024, DNA barcoding and morphology revealed the existence of seven new species of squat lobsters in the family Munididae (Decapoda, Galatheoidea) in the southwestern Pacific, ZooKeys 1188, pp. 91-123 : 91

Typhlonida eluminata sp. nov.

Fig. 10

Typhlonida sp.: Machordom et al. 2022: fig. 3H, table 2.

Material.

Holotype: New Caledonia, Exbodi Stn DW 3941, 19°04'S, 164°03'E, 980-1090 m, 28 September 2011: female, 6.6 mm (MNHN-IU-2011-6787).

Description.

Carapace: Slightly longer than broad, feebly convex, with a few secondary striae between main transverse ridges and some scales on gastric and anterior branchial areas. Dorsal ridges with dense short plumose setae, and a few scattered long setae. Gastric region with two pairs of epigastric spines, longest pair behind supraocular spines. Parahepatic, branchial dorsal and postcervical spines absent. Frontal margins slightly oblique. Lateral margins slightly convex. First lateral spine at anterolateral angle, well-developed, reaching level of sinus between rostrum and supraocular spines; one small spine in front of anterior branch of cervical groove. Branchial margins slightly convex, with five spines, decreasing in size posteriorly. Rostrum spiniform, ~ 0.5 × length of remaining carapace, horizontal. Supraocular spines reaching midlength of rostrum and exceeding end of cornea, subparallel, directed slightly upwards. Pterygostomian region ending in round tip.

Thoracic sternum: Approximately 0.7 × as long as wide. Surface of thoracic IV-VI sternites smooth, with a few short striae in sternite IV. Sternite III ~ 4 × as wide as long. Sternite IV triangular, anterior margin clearly narrower than preceding sternite, anterolateral margins slightly convex; 2.0 × as wide as long, 2.3 × as wide as sternite III.

Pleon: Pleomere II tergite with three-four pairs of spines along anterior ridge, with one uninterrupted transverse ridge on tergite behind anterior ridge; tergites III and IV each with additional ridge behind anterior ridge; ridges with some short setae and a few iridescent setae.

Eye: Cornea not dilated, as wide as peduncle. Maximum corneal diameter <0.3 × distance between bases of anterolateral spines.

Antennule: Article 1 (basal) 0.7 × as wide as long, with two well-developed distal spines, distomesial spine shorter than distolateral; two lateral spines, distal much longer than proximal and not reaching distolateral spine.

Antenna: Article 1 with short distomesial spine reaching end of article 2. Article 2 with subequal distomesial and distolateral spines not reaching end of article 3; article 3 with well-developed distomesial spine.

Mxp3: Ischium with strong distal spine on flexor margin. Merus shorter than ischium; flexor margin with two well-developed spines, proximal stronger than distal; extensor margin unarmed. Carpus unarmed.

P1: 2.2 × carapace length, with dense long setae along mesial and dorsal margins of articles, more numerous in paratypes than in holotype. Merus 0.9 × length of carapace, 2.1 × as long as carpus, with some dorsal and mesial spines; distal spines strong, distomesial spine nearly reaching proximal 1/3 of carpus. Carpus 0.9 × length of palm, 2.0 × as long as broad, with strong spines along mesial margin, some small spines on dorsal side. Palm 2.0 × as long as broad, with row of small dorsal spines; well-developed spines along lateral and mesial margins. Fingers 1.2 × as long as palm; movable finger unarmed, fixed finger with distal spine.

P2-P4: Moderately long and slender, with some plumose setae and scattered longer setae along extensor margin of articles. P2 2.0 × carapace length. Meri successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.7 × length of P3 merus); P2 merus 0.8 × length of carapace, 5.2 × as long as broad, 1.5 × as long as P2 propodus; P3 merus 5.0 × as long as broad, 1.3 × as long as P3 propodus; P4 merus 4.0 × as long as broad, 1.2 × length of P4 propodus. Extensor margins of P2-P4 meri with row of spines, decreasing in size proximally; flexor margins with well-developed distal spine followed proximally by several spines or eminences; lateral sides unarmed. Carpi with distal spine on extensor margin of P2-P4; lateral surface with several granules sub-paralleling extensor margin on P2-P4; flexor margin with distal spine. Propodi 7.5 (P2) to 6.0 (P4) × as long as broad; extensor margin unarmed; flexor margin with five or six slender movable spines on P2-P4, distal end with one fixed spine. Dactyli slender, 0.6-0.7 × as long as propodi; flexor margin with seven-eight movable spinules, with ultimate spinule at base of unguis, penultimate spine equidistant between antepenultimate and ultimate spines; P2 dactylus 4.5 × as long as wide.

Genetic data.

COI, 16S, 18S.

Etymology.

From the Latin, eluminatus, blinded, in reference to the small eyes.

Remarks.

Typhlonida eluminata belongs to the group of species having five minute spines on the branchial lateral margins of the carapace, short supraocular spines, eyes small, cornea as wide as peduncle, maximum corneal diameter <0.3 × distance between bases of anterolateral spines, the anterior ridge of the pleomere II tergite with spines and the distomesial spine of the antennal article 1 well-developed, exceeding midlength of article 2. The new species is closely related to T. typhle (Macpherson, 1994), from New Caledonia and T. galalala ( McCallum et al., 2021) from NW Australia.

The new species can be distinguished from T. typhle by the presence of a distomesial spine on the antennal article 3 in the new species, which is absent in T. typhle . Furthermore, the anterolateral spine of the carapace clearly not reaching the level of the sinus between the rostrum and the supraocular spines in T. typhle , whereas this spine is reaching this sinus in the new species. Finally, the flexor margin of the Mxp3 merus has two well-developed spines in the new species, whereas there is only one median spine in T. typhle .

The differences between T. typhle and T. galalala are the following:

The anterolateral spine of the carapace is as long as the supraocular spine in the new species, whereas it is smaller in T. galalala .

The P2 merus is longer than the carapace in T. galalala , whereas it is shorter in the new species.

The dorsal surface of the P1 palm is unarmed in T. galalala , whereas there are some small spines in the new species.

Genetically the new species is different from T. typhle and T. galalala: T. eluminata diverges respect to T. typhle 3.97% for 16S and 11.42% for COI, and the values are ~ 11.61% for COI and 3.86% for 16S compared to T. galalala .

The new species is also close to T. lanciaria ( Cabezas et al., 2011), from Taiwan, but this species has the cornea clearly wider than the peduncle. Furthermore, both species are genetically quite different (3.01% for 16S) and 13. 4% (COI).

Distribution.

New Caledonia, between 980 and 1090 m.

Figures

Figure 10. Typhlonida eluminata sp. nov., female holotype, 6.6 mm (MNHN-IU- 2011 - 6787), New Caledonia A carapace and pleon, dorsal view B sternal plastron C cephalic region, showing antennular and antennal peduncles, ventral view D right Mxp 3 ischium and merus, lateral view E right P 1, dorsal view F right P 2, lateral view G dactylus of right P 2, lateral view H right P 4, lateral view. Scale bars: 1.0 mm (A, E, F, H); 0.6 mm (B, C, D, G).