Paramunida akaina, Cabezas & Chan, 2014

Cabezas, Patricia & Chan, Tin-Yam, 2014, Deep-sea squat lobsters of the genus Paramunida Baba, 1988 (Crustacea: Decapoda: Munididae) from the Philippines Panglao 2004, Panglao 2005 and Aurora 2007 expeditions, with the description of three new species, Raffles Bulletin of Zoology 62, pp. 302-316 : 304-306

Paramunida akaina , new species

( Fig. 1 )

Material examined. Holotype: AURORA 2007, Philippines, ovigerous female (CL 5.7 mm) (NMCR), station CP2667, 15°56'N, 121°47'E, 292–307 m, 21 May 2007 . — Paratypes: PANGLAO 2004, Philippines, 1 male (CL 6.0 mm), 1 female (CL 5.4 mm), 1 ovigerous female (CL 6.7 mm) ( NTOU A01411), station L42, 9°31.2'N, 123°40.7'E, 80–90 m, 2 July 2004 . — 1 male (CL 6.1 mm), 4 females (CL 6.7–7.7 mm), 2 ovigerous females (CL 6.5–7.1 mm) ( NTOU A01412), station T37, 9°28.2'N, 123°50.7'E, 134–190 m, 04 July 2004 . — AURORA 2007, Philippines, 4 males (CL 5.2–6.4 mm), 1 female (CL 6.5 mm), 10 ovigerous females (CL 5.6–6.8 mm) ( NTOU A01413), station CP2667, 15°56'N, 121°47'E, 292–307 m, 21 May 2007 .

Description. Carapace: As long as broad. Dorsal surface covered with numerous spinules; with few short simple setae. Epigastric region with two spines, each behind supraocular spine; without median row of spinules behind rostral spine. Mesogastric region with one well-developed spine usually merged with a smaller spine. Anterior branch of cervical groove with short setae. Cervical groove distinct. Cardiac and anterior branchial regions slightly circumscribed. Cardiac region with a median row of three well-developed spines, first thicker than others. Each branchial region with row of spines near cardiac region. Frontal margin slightly concave. Lateral margins convex, with some spines and iridescent setae on anterior half. Anterolateral spine well developed, exceeding sinus between rostral and supraocular spines. Rostral spine spiniform, with thin dorsal longitudinal carina; supraocular spines well developed, shorter and slightly slender than rostral spine; margin between rostral and supraocular spines slightly concave ( Fig. 1A, B ).

Sternum: Thoracic sternite 4 with few arcuate striae; sternites 5–7 smooth ( Fig. 1C ).

Abdomen: Abdominal somites 2–3 each with four welldeveloped spines on anterior ridge, posterior ridge with two median spines. Abdominal somite 4 with four spines on anterior ridge; posterior ridge without distinct single median spine. Ridges with numerous spinules and a few small spines ( Fig. 1A ).

Eyes: Maximum corneal diameter about one-third distance between bases of anterolateral spines.

Antennule: Article 1 exceeding corneae, with distomesial spine small and slightly shorter than distolateral; about twice longer than wide and with fringe of long setae along lateral margin; lateral margin with straight (distal) portion clearly shorter than convex (proximal) portion ( Fig. 1D ).

Antenna: Anterior prolongation of article 1 clearly overreaching antennular peduncle by about one-sixth of its length. Article 2 about 2.5 times length of article 3 and 2.5 times longer than wide, ventral surface with scales; distomesial spine slightly mucronated, exceeding antennal peduncle and without tuff of setae, overreaching mid-length of anterior prolongation of article 1, and far from distal end of antennular article 1, distolateral spine not reaching end of article 3; article 3 about 1.5 times longer than wide and unarmed ( Fig. 1D ).

Maxilliped 3: Ischium about 1.6 times length of merus measured along extensor margin, flexor margin bearing long distal spine; merus with well-developed median spine on flexor margin; extensor margin unarmed ( Fig. 1E ).

Pereopod 1: Long and slender, squamate, between 3.1–3.2 times carapace length; carpus about as long as palm, and 11.1–11.3 times longer than height; palm 1.4–1.5 times fingers length. Base of carpus without bundle of setae ( Fig. 1F ).

Pereopods 2–4: Long and slender, with scales on lateral sides of meri, carpi and propodi; scales with short setae. P2 2.5–2.9 times carapace length, merus 1.1–1.2 times longer than carapace, about 14–15 times as long as height, 4.3–4.4 times as long as carpus and 1.6–1.7 times as long as propodus; propodus about 14–15 times as long as height, and 1.1 times dactylus length. Merus with well-developed spines on extensor border, increasing in size distally, flexor margin with few spines and one well-developed distal spine; bearing row of small spines along flexolateral margin. Carpus with few small extensor spines, bearing small distal spine on extensor and distal margins. Propodus with small movable flexor spines. Dactylus compressed, slightly curved, with longitudinal carinae along mesial and lateral sides, flexor border unarmed. End of P2 carpus not reaching end of P1 merus. P3 with similar spination and article proportions as P2; merus slightly longer than P2 merus; propodus and dactylus longer than those of P2. P4 about as long as P2; merus as long as carapace length; propodus and dactylus as long as those of P3; merocarpal articulation clearly exceeding end of anterior prolongation of article 1 of antennal peduncle ( Fig. 1 G–I).

Remarks. Paramunida akaina , new species, belongs to the group of species with the rostral spine larger than supraocular spines, distomesial spine of antennal article 2 mucronated and mesogastric region with one or two spines. The new species is morphologically closely related to P. belone Macpherson, 1993 , but they can be easily distinguished by the following characters:

- The distomesial spine of the antennal article 2 overreaches the antennular peduncle in P. belone , but is far from distal the end of antennular peduncle in P. akaina , new species.

- The distolateral spine of the antennal article 2 not reaching end of article 3 in the new species, instead of overreaching article 3 as in P. belone .

The genetic divergence between P. akaina , new species, and P. belone are in the range of 9.6–10.4% for the ND1 and between 4.6–5.5% % for the 16S.

The new species is also very similar to P. spica Cabezas, Macpherson & Machordom, 2010 ; however, both species chiefly differs in the number of mesogastric spines (three in P. spica versus one in P. akaina , new species). The article 3 of the antenna is nearly twice longer than wide in P. spica , but only 1.5 times longer than wide in the new species. The genetic divergence between P. akaina , new species, and P. spica are in the range of 9.6–10.1% for the ND1 and between 5.5–5.9% for the 16S.

Paramunida akaina , new species, can be also allied with P. antipodes Ahyong & Poore, 2004 , but the distomesial spine of the antennal article 2 clearly overreaches antennal peduncle in the new species, but never reaches it in P. antipodes . No molecular data are available for P. antipodes .

Colour. Not known.

Etymology. From the Greek “akaina”, which means thorn or spine, in reference to the spine merged to the welldeveloped mesogastric spine. The name is considered as a noun in apposition.

Distribution. Philippines, between 80–307 m depth.

Figures

Fig. 1. Paramunida akaina, new species, ovigerous female holotype, 5.7 mm (NMCR). Philippines. A, carapace and abdomen, dorsal view; B, carapace, lateral view; C, thoracic sternum; D, left antennule and antenna, ventral view; E, right maxilliped 3, lateral view; F, right P1, dorsal view; G, left P2, lateral view; H, left P3, lateral view; I, left P4, lateral view. Scale bars = 2 mm.