Paramunida aurora, 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 : 308-310

Paramunida aurora , new species

( Fig. 3 )

Material examined. Holotype: AURORA 2007, Philippines, 1 ovigerous female (CL 6.2 mm) (NMCR), station CP2748, 15°56'N, 121°45'E, 247–249 m, 2 June 2007 . — Paratypes: AURORA 2007, Philippines, 10 males (CL 4.2–6.2 mm) , 8 females (CL 5.5–7.1 mm), 6 ovigerous females (CL 5.6–6.6 mm) ( NTOU-A01416 ), station CP2655, 16°03'N, 121°54'E, 189 m, 20 May 2007 . — 3 males (CL 6.0– 6.4 mm), 6 females (4.8–7.2 mm), 2 ovigerous females (5.9–7.6 mm) (NTOU- A01417), station CP2748, 15°56'N, 121°45'E, 247–249 m, 2 June 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. Gastric region indistinctly separated from hepatic area, metagastric region well defined and mesogastric region without well-developed spines. Anterior branch of cervical groove with short setae. Cervical groove deeply excavated. Cardiac and anterior branchial regions well defined, slightly convex, round scale-like ridge at anterior end of branchiocardiac boundary distinctly elevated and provided with few spinules. Cardiac region with one well-developed spine. Each branchial region with one spine near cardiac region. Frontal margin slightly concave. Lateral margins convex, with iridescent setae on anterior half. Anterolateral spine well-developed, slightly exceeding sinus between rostral and supraocular spines. Rostral spine spiniform, without thin dorsal longitudinal carina; supraocular spines as long as and slightly slender than rostral spine; margin between rostral and supraocular spines slightly concave ( Fig. 3A, B ).

Sternum: Thoracic sternite 4–6 with numerous striae ( Fig. 3C ), sternite 7 with fewer striae.

Abdomen: Abdominal somites 2–3 each with four spines on anterior ridge, posterior ridge with two median spines. Abdominal somite 4 with four spines on anterior ridge; posterior ridge with distinct single median spine. Ridges with numerous spinules and a few small spines ( Fig. 3A ).

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

Antennule: Article 1 exceeding corneae, with distomesial spine 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. 3D ).

Antenna: Anterior prolongation of article 1 overreaching antennular peduncle by about one-fifth of its length. Article 2 about 1.5 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. 3D ).

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

Pereopod 1 (broken): Long and slender. Merus distinctly longer than carapace, dorsally armed with row of spines, and about 19 times longer than height ( Fig. 3F ).

Pereopods 2–4: Long and slender, with scales on lateral sides of meri, carpi and propodi; scales with short setae. P2 4.1–4.2 times carapace length, merus 1.8–1.9 times longer than carapace, about 23–24 times as long as height, 4.1–4.7 times as long as carpus and 1.6–1.7 times as long as propodus; propodus about 16–19 times as long as height, and 1.3–1.4 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. Carpus with few small extensor spines, bearing small distal spine on extensor and flexor 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 as long as P2 merus; propodus and dactylus longer than those of P2. P4 about as long as P2; merus 1.8–1.9 times carapace length; propodus and dactylus as long as those of P3; merocarpal articulation clearly exceeding anterior prolongation of article 1 of antennal peduncle ( Fig. 3 G–I).

Remarks. Paramunida aurora , new species, belongs to the group of species with the rostral spine as long as supraocular spines, distomesial spine of antennal article 2 slightly mucronated and mesogastric region without well developed spines. The new species is closely related to P. tenera Cabezas, Macpherson & Machordom, 2010 , but they can be distinguished by the following morphological characters:

- The rostral spine is short and triangular, with thin dorsal carina in P. tenera , but longer, spiniform and without dorsal carina in the new species.

- The cardiac region has one well-developed spine in P. aurora , new species, whereas there is a row of 3 welldeveloped spines in P. tenera .

- The number of striae at the thoracic sternites 4–7 is distinctly higher in P. aurora , new species, than in P. tenera .

The genetic divergence between P. aurora , new species, and P. tenera are in the range of 11.3–12.6% for the ND1 and between 4.6–4.8% for the 16S.

The new species is also morphologically very close to P. setigera Baba, 1988 , but they clearly differ in the shape of the rostrum (spiniform in P. aurora , new species, but triangular in P. setigera ). The genetic divergence between P. aurora , new species, and P. setigera are in the range of 10.8–11.7% for the ND1 and between 5.5–6.0% for the 16S.

Colour. Not known.

Etymology. The name refers to the deep-sea expedition “ AURORA ”.

Distribution. Philippines, between 189–249 m depth.

Figures

Fig. 3. Paramunida aurora, new species, ovigerous female holotype, 6.2 mm (NMCR). Philippines. A, carapace and abdomen, dorsal view; B, carapace, lateral view; C, thoracic sternum; D, right 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.