Paramunida leptotes, Macpherson, Enrique & Baba, Keiji, 2009

Macpherson, Enrique & Baba, Keiji, 2009, New species of squat lobsters of the genera Agononida and Paramunida (Crustacea: Decapoda: Anomura: Galatheidae) from the western Pacific, Zootaxa 2024, pp. 56-68 : 63-66

Paramunida leptotes n. sp.

( Figs. 5 , 6 )

Munida proxima Baba, 1982: 110 , fig. 4 (Izu Shoto, 33°05.4’N, 139°58.7’E, 430 m). — Baba in Baba et al., 1986: 173, 291, fig. 124 (Kyushu-Palau Ridge and off Amami-oshima of the Ryukyus, 320–400 m). — Wu et al., 1998: 143, figs 40, 42F ( Taiwan). — Baba, 2005: 199 (remarks) (not Paramunida proxima (Henderson, 1885)) .

Material examined. TAIWAN. NE Taiwan, Stn CD 380, 24°38.598’N, 122°10.436’E, 329–456 m, 25.07.2007: male holotype (10.3 mm) ( NTOU A00891 ). — NE Taiwan, Su-ao, Yilan County, 22.05.1990: 1 ovigerous female paratype (12.8 mm) ( NTOU A00892 ).

Etymology. The specific name is a noun in apposition from the Greek leptotes (slenderness), alluding to a slender third segment of the antennule, a character to separates the species from Paramunida proxima ( Henderson, 1885) .

Description. Carapace as long as broad. Dorsal surface covered with spinules, with some scattered spines and short uniramous setae. Gastric region distinctly separated from hepatic area, metagastric region welldefined; 2 epigastric spines behind supraocular spines, and 1 well-developed median spine. Cervical groove distinct. Cardiac region well circumscribed, feebly convex, with 1 well-developed anterior spine followed behind by 1 or 2 small spines in midline. Anterior branchial region distinctly separated from posterior branchial region. Frontal margin slightly concave behind eye. Anterolateral spine strong, reaching sinus between rostral and supraocular spines. Rostral spine spiniform, with thin dorsal longitudinal carinae; supraocular spines well developed and half as long as and more slender than rostral spine. Lateral margins slightly convex, with some uniramous iridescent setae and some plumose non-iridescent setae.

Thoracic sternite with numerous arcuate striae; anterior margin of third sternite slightly convex. Anterior part of fourth sternite contiguous to median part of posterior margin of third sternite.

Two well-developed submedian spines on anterior and posterior ridges of second and third abdominal somites. Fourth abdominal somite similar to preceding ones, but posterior ridge without distinct median spine. Some small spines and spiniform granules along anterior and posterior ridges of each somite.

Eye large, maximum corneal diameter about 0.3 distance between bases of external orbital spines.

Basal segment of antennule (distal spines excluded) overreaching corneae, with small distomesial and distolateral spines. First segment of antennal peduncle with anterior prolongation overreaching antennular peduncle, with long iridescent setae along lateral margin. Second segment (spines excluded) twice length and twice breadth of third segment, and twice longer than wide; distomesial spine long, not mucronated, clearly exceeding antennal peduncle by length of third segment; distolateral spine not overreaching third segment; ventral surface with striae; iridescent long setae along lateral border. Third segment elongate, 1.5–1.7 times longer than wide, and unarmed.

Mxp3 ischium about 1.5 times length of merus measured along dorsal margin, flexor margin with welldeveloped distal spine. Merus with well-developed spine on flexor margin; extensor margin unarmed.

P1 long and slender, 5–6 times carapace length, squamate, with short setae more dense along mesial margins. Merus twice carapace length. Carpus more than 5 times longer than high. Palm as long as carpus, 1.2–1.3 times finger lengths. Merus, carpus and palm with row of spines along mesial margin; merus and carpus with additional row of spines along dorsal side. Movable finger without spine, fixed finger with subterminal spine on lateral margin.

P2–4 long and slender, subequal in length, with numerous scales on lateral sides of meri, carpi and propodi; some uniramous iridescent setae and some plumose non-iridescent setae along dorsal and ventral borders. P2 about 4 times carapace length; merus 1.5–1.7 times longer than carapace, about 11 times longer than high, 4.0–4.5 times as long as carpus and 1.4–1.6 times as long as propodus; propodus 9.5–10 times longer than high, and 1.3–1.4 times dactylus length. Merus with well-developed dorsal spines increasing in size distally, ventral margin with well-developed distal spine and few spines proximal to it; row of small spines along ventrolateral margin. Carpus produced into spine on extensor and flexor margins, with several small extensor marginal spines. Propodus with a few small movable flexor spines. Dactylus compressed, curved distally, with longitudinal carinae along mesial and lateral sides, flexor border unarmed. P2 carpus reaching end of P1 merus. P3 and P4 with similar spination and article proportions to P2. Mero-carpal articulation of P4 clearly exceeding end of anterior prolongation of first segment of antennal peduncle.

Color in life. Specimens from off Amami-oshima, Ryukyu Islands: carapace and abdomen totally but unevenly reddish; gastric region deep red, anterior branchial region pale, median gastric and median cardiac spines distally whitish. Pereopods pale, with brilliant red bands (Baba in Baba et al., 1986: 172–173, fig. 124).

Remarks. As mentioned in the introduction, Baba (2005) noted that the material reported under P. proxima by Baba (1982, 1986) and Wu et al. (1998) from Izu Shoto off Honshu, Japan, the Kyushu-Palau Ridge, off Amami-oshima of the Ryukyus and Taiwan belongs to an undescribed species, enumerating the differences between. Paramunida proxima is known from the Philippines, Indonesia and Admiralty Islands, at 275430 m ( Baba et al. 2008).

The differences between the two species are as follows: (1) the posterior ridge of the fourth abdominal segment is unarmed in P. leptotes , whereas in all the specimens of P. proxima including the type this ridge has a distinct median spine; (2) the distomesial spine of the second segment of antenna is long, not mucronated, and clearly exceeds the antennal peduncle by the length of the third segment in P. l e p t o t e s, whereas this spine terminates in the distal end of the peduncle in P. p ro x i m a; and (3) the third segment of the antenna in P. leptotes is more elongate, being 1.5–1.7 times longer than wide instead of being as long as in P. proxima .

Distribution. Izu Shoto in 430 m, Kyushu-Palau Ridge and off Amami-oshima of the Ryukyus in 320–400 m, and Taiwan in 300 m.

Figures

FIGURE 5. Paramunida leptotes n. sp. Male holotype, 10.3 mm (NTOU A 00891). Taiwan. Carapace and abdomen, dorsal. Scale: 2 mm.

FIGURE 6. Paramunida leptotes n. sp. Male holotype, 10.3 mm (NTOU A 00891). Taiwan. A, sternum. B, left antennule and antenna, ventral. C, ischium and merus of right third maxilliped, lateral. D, right P 1, dorsal. E, right P 2, lateral. F, right P 3, lateral. G, right P 4, lateral. Scale: D – G = 0.5 mm; B, C = 2 mm; A = 1 mm.