Munida acacia, Ahyong, Shane T., 2007

Ahyong, Shane T., 2007, Decapod Crustacea collected by the NORFANZ Expedition: Galatheidae and Polychelidae, Zootaxa 1593, pp. 1-54 : 15-19

Munida acacia sp. nov.

( Fig. 9 , 10A )

Type material. Holotype: NMNZ, ovigerous female (10.6 mm), West Norfolk Ridge, 34°37.81’S, 168°58.59’E, 508–560 m, TAN0308/149 #014, 3 Jun 2003.

Diagnosis. Carapace margins with 5 spines posterior to cervical groove; with parahepatic and postcervical spine; frontal margins faintly sloping posteriorly. Rostrum spiniform. Sternites 5–7 smooth. Abdominal tergite 2 with row of spines along anterior ridge; tergite 3 unarmed. Maximum corneal diameter about half basal distance between anterolateral spines. Antennular basal segment terminal spines subequal. Antennal basal segment with strong mesial spine, apex reaching base of segment 3. Maxilliped 3 merus extensor margin with small distal tooth. Cheliped almost twice carapace length; pollex ventral margin unarmed; carpus about 2.5 times as long as high. Pereopods 2 and 3 propodus extensor margins spinose proximally; dactyli with distalmost movable flexor spine at base of corneous unguis.

Description. Carapace: Transverse ridges well-spaced, generally entire, with very few secondary striae an anterior half and anterior portion of posterior half; gastric and branchial regions with several short striae; hepatic region smooth; cervical groove distinct; with pair of distinct epigastric spines behind supraocular spines, flanked mesially by 1 and laterally by 2 or 3 smaller spines; with 1 parahepatic and 1 postcervical spine. Frontal margins faintly sloping posteriorly; rostrum spiniform, horizontal, three times as long as supraocular spines and more than half-remaining carapace length. Supraocular spines parallel. Anterolateral spines situated at anterolateral angle, slightly divergent, not extending to base of sinus between rostrum and supraocular spine. Margins of carapace anterior to cervical groove with 2 spines (including anterolateral); with 5 spines posterior to cervical groove.

Sternum: Sternite 3 broad, anterior margin sinuous, rounded laterally. Sternite 4 with 2 pairs of minute striae, otherwise smooth; anterior margin broadly and evenly convex. Sternites 5–7 smooth. Ridges demarcating sternites smooth or slightly crenulate.

Abdomen: Tergite 2 with 7 spines along anterior ridge; with 1 uninterrupted transverse stria and 2 short arcuate striae laterally. Tergites 3 and 4 unarmed, each with 1 medially interrupted and 1 entire transverse stria and short lateral striae. Tergite 5 with 2 uninterrupted transverse striae and short lateral striae.

Eye: Large, with maximum corneal diameter about half basal distance between anterolateral spines; peduncle with long distal setae.

Antennule: Basal segment elongate, slightly overreaching cornea, with scattered ventral striae; terminal spines subequal; with 2 lateral spines, distal markedly longer than proximal.

Antenna: Basal segment with strong mesial spine, apex reaching base of segment 3. Segment 2 with 1 or 2 small spines and acute granule on mesial margin; distomesial spine overreaching segment 4; distolateral spine reaching end of segment 3. Segments 3 and 4 unarmed.

Maxilliped 3: Ischium with strong distal flexor spine and minute distal extensor spine. Merus shorter than ischium; flexor margin with strong distal and proximal spine; extensor margin with small distal tooth.

Pereopod 1 (cheliped): About 1.9 times carapace length; sparsely setose; with scattered striae and granules and multiple rows of small spines. Dactylus slightly longer than palm; with 5 small proximal spines and distal spine; occlusal margin denticulate, without gape. Propodus palm almost three times as long as high, with dorsal, medial and ventral rows of spines, longest dorsally. Pollex with 2 subdistal spines, and row of lateral spines; ventral margin unarmed. Carpus about 2.5 times as long as high, slightly shorter than palm; with dorsal, medial and ventral rows of spines, longest dorsally. Merus with strong distal and dorsal spines, longest not reaching proximal quarter of carpus; lateral surface granulate or minutely denticulate, with row of 6–8 small spines.

Pereopod 2: Merus with 11–13 extensor and 7 or 8 graded flexor spines. Carpus with 4 extensor spines and distal flexor spine. Propodus 4.0 times as long as high; extensor margin with 4 or 5 spines proximally; flexor margin with 11 or 12 small movable spines. Dactylus 0.6 propodus length; flexor margin with 8 movable spines, distalmost spine at base of corneous unguis.

Pereopod 3: Merus with 8 or 9 extensor and 6 or 7 graded flexor spines. Carpus with 5 extensor spines and distal flexor spine. Propodus 4.7 times as long as high; extensor margin with 4–6 spines proximally; flexor margin with 10 small movable spines. Dactylus 0.6 propodus length; flexor margin with 8 movable spines, distalmost spine at base of corneous unguis.

Pereopod 4: Merus with 4–7 extensor and 3 or 4 graded flexor spines. Carpus extensor margin unarmed; with distal flexor spine. Propodus 4.5 times as long as high; extensor margin unarmed; flexor margin with 6 or 7 small movable spines. Dactylus 0.6 propodus length; flexor margin with 7 or 8 movable spines, distalmost spine at base of corneous unguis.

Colour in life. Base colour translucent white. Carapace and abdomen pale orange; spines red. Chelipeds pale, diffuse orange; spines red; carpus with red distal patch; fingers whitish with two distal red bands. Etymology. Named acacia, Latin , after a genus of thorny Gondwanan plants, alluding to the spinose extensor margin of the propodi of pereopods 2 and 3.

Remarks. Munida acacia sp. nov. closely resembles M. icela sp. nov. and M. spinicruris Ahyong & Poore, 2004 from Australia in bearing five spines on the branchial carapace margins, a row of spines along the anterior ridge of abdominal tergite 2, and armed dorsal margins of the propodi of the first two walking legs. Munida acacia is readily distinguished from M. icela and M. spinicruris by the smooth rather than granular posterolateral surface of sternite 7. Munida acacia further differs from M. icela by posteriorly sloping rather than transverse anterolateral margins of the carapace.

Distribution. Presently known only from the West Norfolk Ridge; 508–560 m

Figures

FIGURE 9. Munida acacia sp. nov., ovigerous female holotype, 20.6 mm (NMNZ). A, dorsal view. B, left antennule, ventral view. C, left antenna, ventral view. D, right third maxilliped, lateral view. E, sternum. F, right cheliped, lateral view. G – I, pereopod 2 – 4. Scale: A, F – I = 2.5 mm; B – E = 1.2 mm.

FIGURE 10. A, Munida acacia sp. nov., female holotype, 20.6 mm (NMNZ) B, Munida cerisa sp. nov., male holotype, 16.2 mm, TAN 0308 / 29 (AM). C, Munida collier sp. nov., ovigerous female paratype, 19.7 mm, TAN 0308 / 043 (AM P 73025). D, Munida collier sp. nov., male paratype, 19.6 mm, TAN 0308 / 043 (AM P 73024). E, Munida endeavourae Ahyong & Poore, 2004, ovigerous female, 21.7 mm, TAN 0308 / 009 (NIWA 28077).