Munidopsis guochuani, Dong & Gan & Li, 2021

Dong, Dong, Gan, Zhibin & Li, Xinzheng, 2021, Descriptions of eleven new species of squat lobsters (Crustacea: Anomura) from seamounts around the Yap and Mariana Trenches with notes on DNA barcodes and phylogeny, Zoological Journal of the Linnean Society 192 : -

MUNIDOPSIS GUOCHUANI SP. NOV.

( FIGS 21, 22; SUPPORTING INFORMATION, FIG. S6B, C)

Zoobank registration: urn:lsid:zoobank.org:act:F09F864B-354D-4A92-ACDB-CE0176A023A2

Material examined: Holotype, MBM189201 , one male ( PCL 17.4 mm), stn. FX-DIVE 132, M4 seamount located on the Caroline Plate , West Pacific, 10°23.85’N, 140°09.30’E, 1333 m, coll. Faxian ROV on R / V Kexue, 14 August 2017 . Paratypes: MBM286647 , one male ( PCL 11.1 mm), stn. FX-DIVE 176, Kocebu Guyot of the Magellan seamounts, West Pacific, 17°20.51’N, 153°08.12’E, 1439 m, coll. Faxian ROV on R / V Kexue , 10 April 2018 . MBM286648 , one male ( PCL 12.7 mm), one female ( PCL 12.5 mm), one ovig. female ( PCL 17.0 mm), stn. FX-DIVE 177, Kocebu Guyot of the Magellan seamounts, West Pacific, 17°20.57’N, 153°08.13’E, 1416 m, coll. Faxian ROV on R / V Kexue , 11 April 2018 .

Description: Carapace (excluding rostrum) approximately 1.3 times as long as broad. Frontal margins distinctly oblique, without outer orbital angle. Lateral margins slightly convex, each with three to six prominent spines: small anterolateral spine, one or two spines on anterior branchial margin, one to three spines on posterior branchial margin (spine on lateral base of posterior cervical groove strongest, posterior one or two spines usually reduced); scale-like tubercles and short ridges present among spines, especially on posterior branchial margin. Posterior margin ridged, with a row of spines (sometimes reduced as tubercles) on median part and tubercles laterally. Dorsal surface with regions clearly defined, covered with numerous tubercles; tubercles somewhat scale-like on posterior branchial region, and conical on anterior branchial, cardiac and gastric regions; 6 pairs of strong spines present along dorsal midline: three pairs on gastric region, two pairs on cardiac region (each on anterior and posterior cardiac region) and one pair on intestinal region (usually reduced). Gastric region slightly elevated. Cervical groove distinct. Rostrum distinctly elongate, flat and dagger-shaped, 0.6 times as long as remaining carapace length, 3.9 times longer than broad; lateral margins straight; dorsal surface covered with rugae, weakly depressed proximally. Pterygostomial flaps with broad tubercles on lateral surface; anterior end blunt.

Sternal plastron longer than broad. Sternite 3 three times broader than long, divided into two parts by median groove; anterior margin serrated, with acute anterolateral spines. Sternite 4 1.8 times broader than long, ventral surface divided into two parts by pair of oblique ridges; anterolateral surface depressed and sloping anteriorly, contacting posterior margin of sternite 3 on entire length; posterior surface medially depressed, with longitudinal median groove. Sternites 5–7 medially grooved, seperated with one another with elevated, transverse ridges.

Abdominal tergites unarmed; tergites 2 and 3 each with two transverse ridges medially connected and laterally separated by deep grooves; lateral part of dorsal surfaces with numerous scale-like rugae.

Telson composed of seven distinct plates, covered with scale-like tubercles.

Eyestalk movable. Cornea oval, globular and cupped in anterolateral end of ocular peduncle. Ocular peduncle without eyespine, reaching proximal 0.2 of rostrum.

Antennular peduncle with basal article longer than broad; distal margin armed with strong ventrolateral and dorsolateral (rarely with affiliated spine) spines; lateral face inflated; ventral surface with short rugae.

Antennal peduncle stout, reaching at least proximal half of rostrum. Article 1 immovable, with short distomesial spine. Article 2, article 3 and article 4 unarmed.

Third maxilliped stout. Ischium slightly longer than broad, approximately 0.7 times merus length; distoflexor corner acute; crista dentata well developed. Merus longer than broad, extensor margin rugose; flexor margin with small median spines and strong proximal process (divided into two spines in one paratype); ventral surface with rugae. Carpus short, unarmed. Propodus with distoflexor margin convex.

P1 subequal, distinctly elongate, 4.8 times PCL; each segment covered with numerous scale-like tubercles longitudinally arranged on surfaces and margins and bearing fine setae. Ischium with strong dorsodistal spine; ventrodistal margin anteriorly produced. Merus approximately 1.8 times PCL; distal margin with strong dorsal, mesial, ventral and lateral spines; dorsodistal spine followed by row of spines; distomesial spine strongest, followed by two or three slender spines; ventrodistal spine followed by two or three spines (usually on proximal half) along midline of ventral surface. Carpus approximately 0.6 times merus length; distal margin with strong dorsal, mesial and lateral spines; dorsodistal spine followed by spines and pointed tubercles; distomesial spine occassionally followed by few spines. Palm relatively compressed, approximately 0.7 times merus length, 4.9 times as long as broad; mesial margin with a row of small spines or pointed tubercles. Fingers 0.4 times palm length, slightly spooned distally; occlusal margins straight and denticulate, bearing fringe of simple setae, with several triangular tooth on movable finger.

P2–4 slender, sparsely setose; P2 approximately 2.1 times PCL, falling short of distal margin of P1 merus; lateral surfaces of ischia, meri, carpi and propodi covered with scale-like tubercles. Meri compressed, subequal in breadth but decreasing in length posteriorly; P2 merus approximately 0.7 times of PCL and 4.9 times as long as broad, P3 merus 0.9 times P2 merus length, P4 merus 0.6 times P2 merus length; extensor margin tuberculate, armed with strong distal spine; flexor margin tuberculate, without distinct spine. Carpi subequal in length, approximately 0.4 times P2 merus length; extensor surface with two longitudinal ridges each covered with scale-like tubercles and armed with distinct distal spine, spine on mesial ridge much more prominent; flexor margin unarmed. Propodi subcylindrical, subequal in length and breadth, approximately 0.9 times P2 merus length and 6.7 times as long as broad; extensor margin with scale-like tubercles; flexor margin with four or five movable corneous spines on distal half, including distal pair. Dactyli slender, narrowing distally, approximately 0.6 times propodus length; flexor margin straight, with 12 or 13 movable corneous spines (spines on median part much larger) on entire length, and distal spine closely appressed to claw; each corneous spine located on elevated base.

Pereopods without epipod.

Coloration: Ground colour yellow or yellow-orange; dorsal surface near posterior margin of carapace white.

Habitats: Associated with Tiarannid hydrocoral Stegolaria sp. ; also observed free-living on rocky seafloor of seamounts.

Distribution: Magellan Seamounts and a seamount located on the Caroline Plate, West Pacific; depth 1332–1458 m.

Etymology: The specific name is given in memory of famous Chinese navigator Guo Chuan, who perished on his solo trans-Pacific sailing voyage in 2016.

Remarks: The presence of a row of paired spines on the carapace links the new species to M. spinifer (A. Milne Edwards, 1880) and M. erinacea (A. Milne Edwards, 1880) from the Western Atlantic. The new species can be distinguished from the latter two in having a much elongated P1, unarmed rostrum, unarmed abdominal segments and unarmed extensor margin of P2–4 meri (excluding the distal spine). The remarkably elongated P1 links M. guochuani to M. trachypus Alcock & Anderson, 1894 from the Indian Ocean. In addition to the spine arrangement on the carapace, the new species can be distinguished from M. trachypus in having an unarmed rostrum and less spinose P2–4; M. trachypus has a trifid rostrum and densely spinose P2–4 ( Alcock & Anderson, 1894).

No DNA information for the related species is available for comparative study. The intraspecific genetic distances among the type specimens are 1.0– 1.6% for COI and 0.2–1.2% for 16S.