Munidopsis lauensis Baba and de Saint Laurent, 1992

Munidopsis lauensis Baba and de Saint Laurent, 1992 View in CoL

( Figs. 2–3 View Figure 2 View Figure 3 )

Munidopsis lauensis Baba and de Saint Laurent, 1992: 326 View in CoL , fig. 3 ( type locality: Valufa Ridge, Hine Hina, Lau Basin, BIOLAU 89, Nautile dive BL03, 22°32’S 176°43’E, 1,750 m). — Chevaldonné and Olu, 1996: 291. — Baba, 2005: 290 (key, synonymies). — Martin and Haney, 2005: 478, tabs 1, 2. — Macpherson and Segonzac, 2006: 443, figs. 1–3. — Cubelio et al., 2007: 516, fig. 3. — Baba et al., 2008: 147 (synonymies). — Lin et al., 2013: 93, figs.1, 2. — Thaler et al., 2014: fig. 1 (map). — Niu et al., 2017: fig. 6.5a (photograph). — Sun et al., 2019: record. — Hwang et al., 2022: fig. 1, tab. 1.

Material examined. 1 male (12.9 × 10.9 mm) ( NIO1014 View Materials /23), Krishna-Godavari Basin , western Bay of Bengal, off Machilipatnam, India, ORV Sindhu Sadhana, stn. SP3, 15°42.93726’N 82°03.82330’E, 1,754.9 m depth, spade corer, 18.III.2018, coll. M.J. Gonsalves. GoogleMaps

Description of the present material. Body smooth ( Fig. 2 View Figure 2 ); carapace ( Figs. 2 View Figure 2 , 3A, B View Figure 3 )with PCL1.2 × CW, dorsal surface gently convex transversely.Rostrum triangular, length0.4timesPCL,carinatedorsally,feeblyupcurved, lateral margins finely serrated along distal one-third portion.Frontal margin strongly oblique; outer orbital spine represented by angular process. Gastric region dilated, bearing 1 pair of distinct anterior transverse striae. Anterior branchial region bearing short striae, anterolateral spine distinct, followed by few minute teeth. Slightly elevated submarginal ridge followed by gently concave posterior margin.

Thoracic sternum ( Fig. 3C View Figure 3 ) smooth; sternite 3 posteriorly narrowed, anterior margin bearing 2 lobes, anterolateral angle terminating in distinct blunt process on each side. Pleon ( Fig. 3D View Figure 3 ) smooth; tergites 2, 3 bearing 1 medially interrupted transverse groove each, that on tergite 2 distinct.Telson ( Fig.3E View Figure 3 ) comprising 10 plates.

Ocular peduncle ( Fig. 3A, B View Figure 3 ) immovable, cornea ovate. First antennular peduncle article ( Fig. 3F View Figure 3 ) unarmed on ventrodistal margin with, distolateral spine distinctly larger than distomesial spine. First antennal peduncle article ( Fig. 3F View Figure 3 ) with distomesial spine reaching distal end of second article, distolateral spine short, not reaching distal end of second article; second article with short distolateral spine not reaching distal end of third article. Maxilliped 3 ( Fig. 3G View Figure 3 ) ischium half as long as merus, distal angles prominent, crista dentata with 27 denticles; merus f lexor margin with 2 small obsolescent spines, dorsal margin with small distolateral spine.

P1 ( Figs. 2 View Figure 2 , 3H–K View Figure 3 ) 1.8 × PCL with long plumose setae. Ischium bearing distomesial spine. Merus with setose striae arranged longitudinally, distoventral and distomesial spines distinct, ventromesial margin bearing 3 spines. Carpus bearing mesial marginal spine at widest distal portion. Palm length 0.7 times finger length, almost as long as broad, mesially with 2 spiniform processes.Fingers distally spooned, occlusal margins crenulate.

P2 ( Fig. 3L View Figure 3 ) merus with row of 9 small tuberculate spines (distalmost largest)on extensor surface, covered with rows of thick setae ( Fig. 3M View Figure 3 ); lateral surface and ventral margin each with rows of obsolescent tubercular processes, flexor margin with distinct distal spine.

Pereopod (not attached to specimen) ( Fig. 3N View Figure 3 ) merus 4.7 × as long as wide, bearing dorsal row of 10 small spines, distalmost largest, lateral surface and ventral margin each bearing rows of obsolescent tubercular processes, ventral margin with distinct distal spine. Carpus with dorsal ridge terminating in distodorsal spine, feebly tuberculate low ridge dorsolaterally parallel to dorsal margin. Propodus obliquely f lattish, dorsal margin bearing obsolescent tubercular processes. Dactylus ( Fig. 3O View Figure 3 ) length 0.7 times propodus length, flexor margin bearing 17 teeth, each accompanied by movable corneous spine; distalmost tooth close to corneous unguis.

Epipods absent.

Distribution. Hydrothermal vents in the SouthWest Pacific at 1,750 m depth at Lau Basin near Fiji, 2,000 m in the North Fiji Basin ( Baba and Saint Laurent, 1992; Thaler et al., 2014), 1,649 m at Brothers Seamount in the Kermadec Arc off New Zealand ( Cubelio et al., 2007), 1,300 –1,900 m at Manus Basin off Papua New Guinea ( Thaler et al., 2014), and 2,023 m at Onnuri Vent Field in the Central Indian Ocean ( Hwang et al., 2022).

Previous reports of M. lauensis from a cold-seep environment were from 1,119 –1,199 m and 1,750 – 2,000 m at Formosa Ridge off Taiwan ( Lin et al., 2013; Dong and Li, 2015; Shen et al., 2016; Yang et al., 2016; Sun et al., 2019).

Remarks. The morphology of the single Indian specimen of M. lauensis largely resembled the type specimens, with the exception of the higher number of teeth (27) on the crista dentata of the third maxilliped ischium (vs. 23–24 in the type series). Three males reported from the Formosa Ridge ( Lin et al., 2013) reportedly possessed a relatively longer P1 palm (as long as finger), along with distinct spines on the mesial margin of P1 merus, which are less prominent in the Indian specimen, and absent in the type series.

The partial mtDNA COI sequence of the Indian specimen is identical (p-distance, 0.0%) ( Tab. 2) to the previously published sequences originating from the Northwestern Pacific Ocean ( KF774316 View Materials ( Lin et al., 2013), and MH717895 View Materials ( Sun et al., 2019)) ( Fig. 4 View Figure 4 ). The partial 16S rRNA sequence is nearly identical (p-distance, 1.25%) to the previously published sequence ( MH717895 View Materials ) from the Formosa Ridge, Taiwan ( Sun et al., 2019).

Munidopsis lauensis View in CoL belongs to the “orophorhynchus” species group of the genus Munidopsis View in CoL , characterized by a mesially placed distal eye-spine, and chelipeds shorter in length than the second pereopods. This group also includes 18 other congeneric species reported from the Atlantic, Indo-Pacific and Southern Oceans ( Tab. 3). Within the “ orophorhynchus” species group, M. lauensis View in CoL shares the absence of epipods from all the pereopods with Munidopsis albatrossae Pequegnat and Pequegnat, 1973 View in CoL , Munidopsis aries (A. Milne-Edwards, 1880) View in CoL , Munidopsis arietina Alcock and Anderson, 1894 View in CoL , Munidopsis centrina Alcock and Anderson, 1894 View in CoL , Munidopsis ceratophthalma Alcock, 1901 View in CoL , Munidopsis granosa Alcock, 1901 View in CoL , Munidopsis platirostris (A. Milne-Edwards and Bouvier, 1894) View in CoL , Munidopsis sharreri (A. Milne-Edwards, 1880) View in CoL , and Munidopsis spinoculata (A. Milne-Edwards, 1880) View in CoL . It differs from M. arietina View in CoL , M. granosa View in CoL , and M. platirostris View in CoL in having a narrow triangular rostrum; from M.sharreri View in CoL in the smooth posterior margin of the carapace; from M. albatrossae View in CoL in possessing moderately arched lateral carapace margins; from M. aries View in CoL and M. centrina View in CoL in the absence of gastric spines on the carapace; and from M. spinoculata View in CoL in the presence of spines on the

Bathymetric

Species Distribution

range in meters

Eastern Pacific ( Alaska Bay, off Oregon, Monterey Bay, Baja California, East Pacific Rise and west of

Munidopsis albatrossae Pequegnat 1920 –3680 Costa Rica, Galapagos Islands), Western Pacific (Weijia Guyot and Hawaii) and Bellingshausen Sea

and Pequegnat, 1973 (Antarctic waters) ( Osawa et al., 2023)

New England, Middle Atlantic Bight, Bequia, Colombian Basin, Venezuelan Basin, south of Azores,

Munidopsis aries (A. Milne-

2615–5320 Iberia abyssal plain, Off Mauritania, Angola, South Africa, Réunion Island ( Baba et al., 2008); Central

Edwards, 1880)

Indian Ridge, South East Indian Ridge,Rodriguez Triple Junction ( Gerdes et al., 2021).

Munidopsis arietina Alcock and Bay of Bengal, Taiwan ( Baba et al., 2008); Great Australian Bight, off the eastern coast of Australia 1836–3852

Anderson, 1894 ( Farrelly and Ahyong, 2019)

Indian Ocean ( Mozambique Channel, Southwest Indian Ocean, Bay of Bengal), Western Pacific

Munidopsis centrina Alcock and

2300–3485 Ocean (south of Tosa Bay, Taiwan, New Caledonia; off the eastern coast of Australia ( Baba et al., 2008;

Anderson, 1894

Farrelly and Ahyong, 2019)

Munidopsis ceratophthalma

677–878 Andaman Sea, West of Sumatra ( Baba et al., 2008)

Alcock,1901

Munidopsis edwardsii (WoodMason, 1891 in Wood-Mason 1379–3065 SW of Sri Lanka, Bay of Bengal, Taiwan, New South Wales ( Baba et al., 2008)

and Alcock, 1891)

Munidopsis granosa Alcock, 1901 View in CoL 2610–3485 Mozambique Channel, Bay of Bengal, Taiwan ( Baba et al., 2008)

Formosa Ridge off Taiwan, South-West Pacific (Lau Basin, North Fiji Basin, Brothers Seamount,

Munidopsis lauensis Baba and de

1119- 2023 Kermadec Arc off New Zealand, Manus Basin off Papua New Guinea), Central Indian Ocean (Onnuri

Saint Laurent,1992

Vent Field) ( Baba et al., 2008) ( Hwang et al., 2022)

Munidopsis livida ( Perrier, 1886) View in CoL 2070–3113 Gulf of Mexico, off Jamaica off Canary Islands, Cape Ghir, off Congo, off Angola ( Baba et al., 2008) Munidopsis marionis View in CoL (A. Milne-

374–1700 Planier Island, Western Tyrrhenian Sea, Levant Basin ( Baba et al., 2008)

Edwards, 1882)

Atlantic Ocean (South West Gulf of Mexico, Guadeloupe, Dominica, Bahamas, Brazil, Gulf of

Guinea), Indian Ocean (off Madagascar, Mozambique Channel, Gulf of Aden, Bay of Bengal), Western

Pacific Ocean (Makassar Strait, off Sulawesi, Moluccas, Philippines, off eastern coast of Australia, off

Munidopsis nitida (A. Milne

592–3680 Admiralty Islands, off Arou Islands, between Papua and Admiralty Islands, Solomon Islands, New

Edwards, 1880)

Caledonia, Vanuatu, Taiwan,Izu Shoto ( Japan); Eastern Pacific (off Oregon, South Eastern Gulf of California, off Mariato Point, Cocos Island, and Gulf of Panama) ( Baba et al., 2008; Farrelly and

Ahyong, 2019)

Munidopsis pallida Alcock,1894 2233–3299 Off Zanzibar, Bay of Bengal, Andaman Sea, Taiwan ( Baba et al., 2008)

Atlantic Ocean (West European Basin, from off Ireland to off South Africa) and Indian Ocean

Munidopsis parfaiti ( Filhol, 1885) View in CoL 2895–5330

( Madagascar) ( Baba et al., 2008)

Munidopsis platirostris (A. Milne- Florida Strait, Yucatan Strait, northwest Caribbean Sea, Bahamas, Lesser Antilles, Puerto Rico,

101–860

Edwards and Bouvier, 1894) Colombia, Venezuela ( Baba et al., 2008; Poupin and Corbari, 2016; Williams et al., 2019)

Munidopsis recta Baba, 2005 View in CoL 2216–3190 Gulf of Panama and East Pacific Rise ( Baba et al., 2008)

Munidopsis sharreri View in CoL (A. Milne- 298–454 Santa Cruz ( Virgin Islands) and Carriacou Island ( Grenada) ( Baba et al., 2008) Edwards, 1880) Munidopsis spinoculata View in CoL (A. Milne- Florida Strait, Gulf of Mexico, Caribbean Sea, Lesser Antilles Dominica, north coast of Cuba, 597–1738 Edwards, 1880) southwest off British Honduras, near Jamaica ( Baba et al., 2008; Poupin and Corbari, 2016)

Munidopsis squamosa View in CoL (A. Milne- Dominican Republic, Yucatan Channel, Lesser Antilles, Islands of the Caribbean ( Baba et al., 2008; 212–500

Edwards, 1880) Poupin and Corbari 2016)

Atlantic Ocean (off Namibia, West of Cape Point), Indian Ocean (Marion Island, Crozets), Western

Munidopsis subsquamosa

1789–4800 Pacific (off Japan, Queensland and New South Wales,) Eastern Pacific (off Oregon, Panama, Chile)

Henderson, 1885

( Baba et al., 2008; Farrelly and Ahyong, 2019)

meri and carpi of pereopods. It closely resembles M. ceratophthalma in possessing a narrow triangular rostrum, absence of gastric spines, moderately arched lateral carapace margins, smooth posterior margin of carapace, the presence of spines on the meri and carpi of pereopods, and absence of epipods on all pereopods. However, M. lauensis differs from M. ceratophthalma in having a relatively shorter mesial eye-spine, which is less than half of the rostral length (vs. relatively longer eye-spine, greater than half of the rostral length in M. ceratophthalma ). An identification key to the species of the “ orophorhynchus” group is provided below.

Identification key to the species of the “ orophorhynchus ” group of the genus Munidopsis :

1. Epipods absent on chelipeds and pereopods .......................................................................................................... 2

– Epipods present on chelipeds, may be absent on pereopods ......................................................................... 11

2. Rostrum styliform, bearing lateral spines ............................................................................................. M. arietina

– Rostrum narrowly to broadly triangular, unarmed laterally ........................................................................... 3

3. Rostrum broadly triangular ........................................................................................................................................ 4

– Rostrum narrowly triangular .................................................................................................................................. 5

4. Carapace uniformly tuberculate. Abdominal somites 2–4 each with sharp median tooth ............................ .......................................................................................................................................................................... M. granosa

– Carapace sparsely tuberculate. Abdominal somites 2–4 unarmed ......................................... M. platirostris

5. Posterior margin of carapace spinose ..................................................................................................... M. sharreri

– Posterior margin of carapace smooth .................................................................................................................... 6

6. Carapace broadest anteriorly, lateral margins converging posteriorly ...................................... M. albatrossae

– Carapace broadest at midlength, lateral margins moderately arched ............................................................ 7

7. Carapace with gastric spines ....................................................................................................................................... 8

– Carapace without spines on the gastric region ................................................................................................... 9

8. Carapace with 1 pair of gastric spines .......................................................................................................... M. aries

– Carapace with 2 transverse rows of gastric spines ........................................................................... M. centrina

9. Surfaces of meri and carpi of chelipeds and pereopods armed with spines or tubercles ............................ 10

– Surfaces of meri and carpi of chelipeds and pereopods unarmed .......................................... M. spinoculata

10. Eye-spine longer than half of rostral length .......................................................................... M. ceratophthalma

– Eye-spine shorter than half of rostral length...................................................................................... M. lauensis

11. Epipods present on chelipeds and first two ambulatory pereopods ................................................................... ...................................................................................................................... M. marionis (A. Milne-Edwards, 1882)

– Epipods present on chelipeds only ..................................................................................................................... 12

12. Rostrum broadly triangular ................................................................................................................................... 13

– Rostrum moderately triangular ........................................................................................................................... 16

13. Carapace with 1 pair of gastric spines .......................................................................... M. pallida Alcock, 1894

– Carapace without gastric spines ........................................................................................................................... 14

14. Abdominal somites 2-4 each with blunt, low median process ............................. M. parfaiti ( Filhol, 1885)

– Abdominal somites 2-4 unarmed ....................................................................................................................... 15

15. Dorsal surface of carapace nearly smooth. Rostrum constricted between eyes ............................................. .................................................................................................................................................. M. livida ( Perrier, 1886)

– Dorsal surface of carapace sharply granulated. Rostrum not constricted between eyes ............................. .................................................................................................................... M. squamosa (A. Milne-Edwards, 1880)

16. Carapace with spines on gastric region ................................................................................................................ 17

– Carapace without spines on gastric region ............................................................................................................. .............................................................................. M. edwardsi (Wood-Mason in Wood-Mason & Alcock, 1891)

17. Carapace with 1 pair of spines only on gastric region ........................ M. nitida (A. Milne-Edwards, 1880) – Carapace with spines in addition to 1 pair of spines on gastric region ........................................................ 18

18. P2–4 dactyli nearly straight on flexor margin ................................................................... M. recta Baba, 2005 – P2–4 dactyli considerably curving ............................................................ M. subsquamosa Henderson, 1885