Munida leeuwin, McCallum & Ahyong & Andreakis, 2021

McCallum, Anna W., Ahyong, Shane T. & Andreakis, Nikos, 2021, New species of squat lobsters of the genus Munida from Australia, Memoirs of Museum Victoria 80, pp. 113-152 : 128-130

Munida leeuwin sp. nov.

http://zoobank.org/urn:lsid:zoobank.org:act:6D615718-C84B-

416F-891A-4D9FABFB7592

Figures 10 , 11

Munida sp. MoV 5176. — Poore et al., 2008: 20: unnumbered colour fig. (lower right) (south-western Australia, 101– 100 m).

Type material. Holotype. WAM C78562 , male (cl 8.1 mm, pcl 5.3 mm), Western Australia, Barrow Island , 20° 59.082' S, 114° 54.42' E to 20° 59.67' S, 114° 54.54' E, 100–101 m, SS10/2005/170, 13 December 2005.

Paratypes (all Western Australia). WAM C78563 , 1 ovigerous female (cl 7.2 mm, pcl 5 mm), 7 females (cl 6.0 mm, pcl 3.8 mm to cl 8.5 mm, pcl 5.5 mm), 7 males (cl 6.3 mm, pcl 3.8 mm to cl 9.1 mm, pcl 6.2 mm), collected with holotype ; NMV J55046 , 1 male (cl 8.7 mm, pcl 5.9 mm), 1 ovigerous female (cl 7.9 mm, pcl 5.2 mm), collected with holotype ; NMV J55100 , 2 ovigerous females (cl 7.7 mm, pcl 5.0 mm; cl 7.8 mm, pcl 5.1 mm), 1 female (cl 7.8 mm, 5.0 mm), collected with holotype ; NMV J56100 , 1 juvenile (cl 4.4 mm, pcl 3.0 mm), 1 ovigerous female (broken rostrum; pcl 4.8 mm), Imperieuse L23 transect, 18° 27.612' S, 120° 08.682' E to 18° 27.72' S, 120° 08.682' E, 80–81 m, SS05/2007/82, 16 June 2007 .

Description. Carapace. Length 1.1 × greatest width, widest at midlength. Dorsal surface with main transverse ridges mostly uninterrupted, without secondary transverse striae between main ridges; ridges and striae lined with short, non-iridescent setae and few long iridescent setae. Gastric region with 5 or 6 pairs of epigastric spines, longest pair behind supraocular spines, with median row of 2 or 3 small spines behind rostrum. Hepatic region with 3 or 4 spines on dorsal surface; parahepatic spines present. Anterior part of branchial region between cervical groove and postcervical groove with 3 ridges and 1 or 2 small spines; 1 postcervical spine; posterior part of branchial region with 4 or 5 main transverse ridges (excluding posterodorsal ridge) and few shorter secondary striae between main ridges. Cardiac region with 3 main transverse ridges. Intestinal region without striae; posterodorsal ridge distinct, without secondary stria. Frontal margin inclined posteriorly at 115° from midline. Lateral margin slightly convex; anterolateral spines parallel, horizontal, not reaching sinus between rostrum and supraocular spine; hepatic marginal spine shorter than anterolateral spine; branchial margin with 5 spines. Rostrum spiniform, slightly sinuous in profile, length 0.5 × pcl; supraocular spine 0.3 × length of rostrum. Epistomial ridge curved, ending anterior to antennal gland; mesial protuberance distinct.

Thoracic sternum. Sternital surface smooth, sternite 4 with few long striae. Sternite 3 0.4 width of sternite 4; midlength of sternal plastron (sternites 4–7) 0.7 width of sternite 7. Sternite 4 anterior margin truncate, entirely contiguous with sternite 3.

Abdomen. Somite 2 without spines. Somites 2–4 each with 2 or 3 uninterrupted striae behind anterior ridge and striae at lateral margins. Somite 6 posteromedian margin almost straight. Telson with numerous transverse squamae; greatest width 2.0 × median length; anterolateral margin concave.

Eye. Maximum corneal diameter 0.35 × distance between anterolateral spines.

Antennule. Basal article (distal spines excluded) not overreaching corneae; distolateral and distomesial spines subequal; 2 lateral spines, proximal smaller, longer lateral spine exceeding distal spines.

Antenna. Article 1 with distomesial spine reaching midlength of article 2. Article 2 distomesial spine slightly overreaching distal margin of article 3; distolateral spine almost reaching distal margin of article 3. Article 3 unarmed or with small distolateral spine. Article 4 unarmed.

Maxilliped 3. Ischium 1.6 × merus length, with distal flexor spine. Merus with 3 well-developed spines on flexor margin; extensor margin with small distal spine.

P1. length 3.1–4.4 pcl (males), 2.8–3.0 pcl (females), with dense covering of iridescent setae on inner margins of merus (without plumose setae), merus 1.3–1.4 (males), 1.0–1.1 (females) × pcl, with row of 5 subtriangular spines on dorsal and mesial margin; distomesial spine not reaching midlength of carpus. Carpus 0.3–0.4 × merus length, length 1.9 (males), 2.0–2.4 (females) × width, with spines along mesial margin. Propodus 1.6–1.7 (males), 1.4 (females) × merus length; fingers 0.4–0.6 (males), 0.5–0.6 (females) × total propodus length; pollex with row of small spines along outer margin; dactylus with 3 small spines on outer margin.

P2–4. Moderately long and slender, with scales on lateral surfaces of meri; extensor margin with plumose setae and iridescent setae. P2 length 2.1–2.6 × pcl; merus as long as carapace, length 6.4 × height, 3.4 × carpus length and 1.3 × propodus length; extensor margin spinose; flexor margin with acute ridges, 1 or 2 spines and well-developed distal spine; carpus with 4 small extensor spines, distal spine on extensor and flexor margin; propodus length 7 × height, with 10–14 movable flexor spines; dactylus compressed, almost straight, 0.7–0.9 × propodus length, length 6–7 × height, flexor margin with 7–12 spines, unarmed along distal 1/3. End of P2 carpus not reaching end of P1 merus. P3 with similar spination and article proportions as P2; merus slightly shorter than P2 merus (0.8); propodus and dactylus as long as those of P2. P4 length 0.8 × P2 length; merus 0.6–0.7 × pcl, 0.9 × P3 merus length; merocarpal articulation almost reaching marginal hepatic spine of carapace.

Genetic data. COI and 16S; see Table 1.

Etymology. Named after the Leeuwin current which flows off the west coast of Australia; used as a noun in apposition.

Remarks. Munida leeuwin sp. nov. is most similar to M. roshanei Tirmizi, 1966 , M. janetae Tirmizi and Javed, 1992 , and M. arabica Tirmizi and Javed, 1992 , described from the western Indian Ocean. These three species are very similar to each other and have been distinguished by the length of the pereopod 1 chela, the ratio of the length of the fingers to the propodus palm, and the shape of sternite 3. In his key, Baba (2005) characterises M. janetae as having cheliped fingers that are distinctly longer than the palm, while the fingers are shorter than the palm in M. roshanei and M. arabica . In M. leeuwin sp. nov., the fingers are usually as long as the palm but are occasionally longer or shorter than the palm (0.4–0.6 × propodus length). We tentatively describe this species as new based on a combination of subtle differences from the aforementioned species and significant molecular divergence from material we identify as M. roshanei . In M. leeuwin sp. nov., the dactlyli of P2–4 are slender and unarmed on the distal one-third of the flexor margin, with the ultimate spine closer to the penultimate spine than the unguis. This differs from M. janetae in which the dactyli have spines regularly arranged along the entire flexor margin (Tirmizi and Javed, 1992). Illustrations of M. arabica show the dactyli to be similar to those of M. leeuwin sp. nov., but M. arabica can be distinguished by the presence of distal spines on antennal article 4, which are always absent in M. leeuwin sp. nov. The type description of M. roshanei lacks a description or illustration of the dactyli, as does that of Lewinsohm (1969) for nearby Red Sea specimens. Specimens identified as M. roshanei from the Phillipines ( Baba, 1988) and Australia (present study), however, have the dactyli with spines regularly arranged along the entire flexor margin. Although the spination of the P2–4 dactyli of the type material of M. roshanei remains to be confirmed, given the brevity of the original description and without access to the type, we fully describe M. leeuwin as new to improve the taxonomy of this difficult group.

The genetic sequences of M. leeuwin are highly divergent from all other species analysed. Despite their morphological similarities, M. leeuwin and our specimens of M. roshanei are divergent by 12% in COI.

Distribution. Presently known only from off Western Australia, 658– 754 m.

Figures

Figure 10. Munida leeuwin sp. nov., holotype, male cl 8.1 mm, pcl 5.3 mm (WAM C78562): A, carapace and abdomen, dorsal view; B, right chela, dorsal view; C, left antenna and antennule, ventral view; D, sternum; E, abdominal somite 6, telson and right uropod. Scale: A–E = 2 mm.

Figure 11. Munida leeuwin sp. nov., holotype, male cl 8.1 mm, pcl 5.3 mm (WAM C78562): A, right P2 dactylus, lateral view; B, right P2, lateral view; C, right P3, lateral view; D, right P4, lateral view; E, left maxilliped 3, lateral view. Scale A–E = 1 mm.