Munida abrolhos, 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 : 115-119

Munida abrolhos sp. nov.

http://zoobank.org/urn:lsid:zoobank.org:act:14DA5265-E0E5-

47B5-B4B0-93296A355921

Figures 1, 2, 3A

Munida sp. MoV 5214. — Poore et al., 2008: 21 (south-western Australia, 201–206 m).

Munida aff. rubiesi . — Poore et al., 2008: 20 (part), unnumbered fig. — McEnnulty et al., 2011: app. 1.

Munida sp. MoV 5526. — Poore et al., 2008: 21.

Munida keiensis . — McEnnulty et al., 2011: app. 1.

Type material. Holotype: WAM C78556 , ovigerous female (cl 23 mm, pcl 14 mm), Abrolhos , Western Australia, 29° 00.594' S, 113° 42.78' E to 29° 01.512' S, 113°43.32'E, 700–704 m, SS10/2005/85, 2 December 2005.

Paratypes (all Western Australia): NMV J55036 , 6 ovigerous females (cl 18.9 mm, pcl 11.2 mm to cl 25.9 mm, pcl 15.7 mm), 6 females (cl 14.0 mm, pcl 8.1 mm to cl 19.0 mm, pcl 12.5 mm), 10 males (cl 15.0 mm, pcl 8.9 mm to cl 22.8 mm, pcl 14.6 mm), collected with holotype ; NMV J55262 , 1 ovigerous female (cl 27.5 mm, pcl 18.3 mm), 1 female (cl 14.5 mm, pcl 8.4 mm), Barrow L1 transect, 20° 59.412' S, 114° 07.896' E to 20° 59.13' S, 114° 08.394' E, 700 m, SS05/ 2007/1, 9 June 2007 ; NMV J55279 , 1 specimen, Mermaid L24 transect, 16° 44.286' S, 119° 15.042' E to 16° 43.794' S, 119° 15.48' E, 693–698 m, SS05/2007/70, 17 June 2007 ; WAM C78557 , 1 male (cl 22.6 mm, pcl 13.0 mm), Ningaloo South , 22° 03.57' S, 113° 43.74' E to 22° 04.026' S, 113° 43.26' E, 658–754 m, SS10/2005/149, 10 December 2005 .

Description. Carapace. Length and width subequal, 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. Gastric region with large pair of epigastric spines behind supraocular spines and 2 or 3 pairs of small epigastric spines; without median row of spines behind rostrum. Hepatic region granular; parahepatic spine present. Anterior part of branchial region between cervical groove and postcervical groove with 1 or 2 ridges and sometimes 1or 2 short striae; postcervical spine present; posterior part of branchial region with 5 transverse ridges (excluding posterodorsal ridge). Cardiac region with 3 main transverse ridges. Intestinal region with 2 lateral striae; posterodorsal ridge distinct, without secondary stria. Frontal margin inclined posteriorly at 110° from midline. Lateral margin slightly convex; anterolateral spines parallel, directed slightly upwards, reaching sinus between rostrum and supraocular spine; hepatic marginal spine anterior to cervical groove, much shorter than anterolateral spine; branchial margin with 4, occasionally 5, spines (additional third spine small). Rostrum spiniform; curving dorsally, 0.6–0.7× pcl; supraocular spine length 0.3 length × rostrum length. Epistomial ridge straight, ending at antennal gland; mesial protuberance distinct.

Thoracic sternum. Median length of sternal plastron (sternites 4–7) 0.6 × width of sternite 7. Thoracic sternites suface smooth, sternites 4 with few striae. Sternite 3 0.5 × width of sternite 4. Sternite 4 anterior margin subtriangular, narrowly contiguous with sternite 3.

Abdomen. Somite 2 with 8–10 large spines, evenly spaced along anterior ridge; with stria behind anterior ridge. Somites 3–4 with 2 striae behind anterior ridge. Somite 6 posteromedian margin slightly concave. Telson with numerous transverse squamae; greatest width 1.6 × midlength; 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 reaching end of distal spines.

Antenna. Article 1 with distomesial spine reaching distal margin of article 2. Article 2 distomesial spine nearly reaching distal margin of article 4; distolateral spine reaching midlength of article 3. Articles 3 and 4 unarmed.

Maxilliped 3. Ischium 1.8 × length of merus, with small flexor distal spine. Merus flexor margin with large spine and small distal spine; extensor margin without distal spine.

P1. 2.0–2.5 pcl, with plumose setae on inner margins, and some iridescent setae, merus 0.8–0.9 pcl, with row of 6 spines on dorsal margin; distomesial spine reaching midlength of carpus. Carpus 0.4 × length of merus, length 0.9–1.1 × width, with 5 spines along the mesial margin. Propodus 1.0–1.4 × merus length, fingers longer than palm, 0.5–0.6 × total propodus length; pollex with subdistal spine, outer margin unarmed; dactylus outer margin unarmed.

P2–4. Long, slender, with few small scales on lateral surfaces of meri, carpi and propodi; extensor margin with plumose setae and few iridescent setae. P2 and P3 similar in length, P4 shorter (P3 merus 0.9–1.0 × length of P2 merus, P4 merus 0.8 × length of P3 merus). P2 1.9–2.1 × pcl; merus 0.6–0.8 × pcl, length 6 × width, 3–4 × carpus length and 1.6 × propodus length, extensor margin with 9 spines including distal spine, flexor margin with 4 spines and well-developed distal spine; carpus with 2 extensor spines a distal flexor spine; propodus length 5.5–6.5 × height, with 5 movable flexor spines; dactylus 0.8–0.9 × propodus length, gently curved, length 6–7 × width, extensor margin densely lined with stiff short setae on distal half, flexor margin with 8 small moveable spines, space between spines increasing distally, unarmed along distal 1/5. End of P2 carpus overreaching end of P1 merus. P3 with similar spination and article proportions as P2; merus, propodus and dactylus as long as those of P2. P4 length 0.85 × P2 length; merus 0.5–0.6 × pcl; merocarpal articulation reaching hepatic marginal spine of carapace.

Egg diameter. 0.5 mm.

Colour. Carapace and abdominal somites 2–3 pink. Rostrum and supraocular spines white. P1 pale pink with white fingers, P2–4 pale pink on meri and carpi, white on propodi and dactyli.

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

Etymology. After the type locality near the Abrolhos Islands; used as a noun in apposition.

Remarks. Munida abrolhos sp. nov. is similar to M. andamanica Alcock, 1894 , M. rosula Macpherson, 1994 , and M. curvirostris Henderson, 1885 , with a dorsally curving spiniform rostrum, P1

G

fixed finger with only subterminal spine (without marginal spines on lateral margin), and abdominal somite 2 with a row of 6–8 spines and at most 4 transverse ridges. Most clearly the new species differs from these species as it usually has only 4 branchial spines, although sometimes a smaller third branchial spine is present. In addition, postcervical spines, present in M. abrolhos sp. nov., are always absent in the aforementioned species.

Of those species with 4 branchial spines, M. abrolhos sp. nov. is most similar to M. keiensis Baba, 2005 , in having subequal distal spines of the basal antennular article, and the distomesial spine of antennal article 2 overreaching article 3 but not distinctly overreaching article 4. The two species can be distinguished by the shape of the anterior margin of thoracic sternite 4, which is broadly rounded in M. keiensis but subtriangular in M. sp. nov.

Sequence divergence between M. abrolhos sp. nov. and M. rosula is 3% for COI and 0.8% for 16S.

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