Munidopsis similis Smith, 1885

Rodríguez-Flores, Paula C., Seid, Charlotte A., Rouse, Greg W. & Giribet, Gonzalo, 2023, Cosmopolitan abyssal lineages? A systematic study of East Pacific deep-sea squat lobsters (Decapoda: Galatheoidea: Munidopsidae), Invertebrate Systematics 37 (1), pp. 14-60 : 47-48

Munidopsis similis Smith, 1885

( Fig. 8 e, f , 18 a–f .)

Munidopsis similis Smith, 1885

Munidopsis asiatica Marin, 2020 , syn. nov.

Material examined

Holotype. USA: Nantucket Shoals, leg. United States Fish Commission, Albatross R/V, Stn 2192, 5.viii.1884, 39.77500°N, 70.24580°W, 1939 m, 1 ov. F 16.7 mm ( USNM 8255 ).

Non-type specimens. USA: Gay Head–Bermuda transect, Atlantic Ocean, leg. R/V Chain 088, Howard L. Sanders, Stn 210A, 2.ii.1969, 39.716644°N, 70.766679°W, 2024 to 2064 m, 1 M 17.5 mm (MCZ IZ-81478). — USA: Hudson Canyon, leg. R/V Knorr 35, Stn 326, 18.xi.1973, 39.200000°N, 71.783333°W, 2288 to 2297 m: 3 M 12.3–22.1 mm, 1 ov. F 18.3 mm, 3 F 12.1–17.9 mm (MCZ IZ-127820). — USA: Hudson Canyon, Atlantic, leg. R/V Knorr 35, Stn 325, 18.xi.1973, 39.221611°N, 71.890043°W, 1919 to 1974 m: 1 M 14.5 mm (MCZ IZ-81527). — USA: rise off New England, Atlantic, leg. R/V Atlantis II 086, Stn 432, 41′ Gulf of Mexico shrimp trawl, 19.iii.1975, 39.52000°N, 70.33333°W, 2450 to 2350 m, 1 M 20.4 mm, 1 F 12.3 mm broken (MCZ IZ-39189). — USA: Atlantic Ocean, leg. R/V Chain 124, Stn 501, 4.vii.1975, 38.33666°N, 70.21833°W, 3287 to 3314 m: 1 M broken (MCZ IZ-81526).

USA: West Cortes Bank, California, leg. R/V Atlantis II, HOV Alvin dive 1508, cruise AT112, Leg 19, Stn MEA 85-5, 19.i.1985, 32.21823°N 119.25998°W, 1538–1678 m, 1 ov. F 12.1 mm (CAS-IZ 190355). — USA: San Diego Trough, off California, leg. Lisa Levin, Larry Lovell and students, R/V Robert Gordon Sproul , otter trawl, 2.x.2005, 32.60000°N, 117.50830°W, 1215 m: 1 M 11.2 mm (SIO-BIC C10923). — USA: San Diego Trough, off California, leg. Lisa Levin and students, R/V New Horizon, otter trawl, 31.x.2009, 32.59600°N, 117.48300°W, 1200 m: 1 not measured (SIO-BIC C11171). — USA: California, leg. E/V Nautilus, ROV Hercules dive H1829, Stn NA123-015-02-B-MCZ, 17.x.2020, 34.87917°N, 121.74157°W, 1295 m: 1 F 12.1 mm (MCZ IZ-162084).

COSTA RICA: Mound Jaguar, leg. Greg Rouse, Avery Hiley, R/V Falkor, ROV SuBastian dive S0230 S3, 25.i.2019, 9.65882°N, 85.88289°W, 1895 m: 1 M 5.8 mm (SIO-BIC C13964).

Diagnosis

Carapace with numerous short scales each with long, stiff setae, laterally with 3–4 spines, cervical grooves distinct. Rostral spine triangular, slender, often dorsally carinated, lateral margin often serrated. Pair of epigastric spines, often with additional small spines. Frontal margins slightly oblique. Orbit not distinctly excavated; outer orbital angle produced into a strong antennal spine. Anterolateral spine of carapace strong. Branchial margin with 3–4 spines. Abdominal somites with transverse ridge, unarmed. Telson divided into 10 plates. Sternite 3 moderately broad, anterolateral angles produced, sternite 4 subtriangular. Eyes fixed, armed with mesial and lateral spines, mesial larger, epistomial spine absent. Article 1 of peduncle with well developed subequal dorsolateral and distolateral spines. Article 1 of antenna with distomesial spines and distolateral spines. Mxp3 merus as long as ischium, subrhomboidal in lateral view. P1 slender, elongate, spinose, fixed finger with denticulate carina on distolateral margin. P2 not reaching end of P1. P2–4 long and slender; dactyli moderately slender, curving, flexor margin with teeth along entire margin decreasing proximally. Epipods absent from all pereopods.

Colouration

Carapace, abdomen, eyes and pereopods whitish.

Distribution

Northwest Atlantic Ocean, Bering Sea and Northeast Pacific, including Costa Rica, from 1390- to 3314-m depth.

Genetic data

COI, 16S rRNA and 28S rRNA.

Remarks

Munidopsis similis was described from southern New England and recorded from the Middle Atlantic Bight, West of Iceland and the Gulf of Mexico ( Smith 1885; Hansen 1908; Wenner 1982; Coykendall et al. 2017). Marin (2020) described a new taxon, M. asiatica , from the Bering Sea, reported as morphologically and genetically very similar to M. similis (see Marin 2020). We discovered new records of M. similis for the Northeast Pacific (USA and Costa Rica). Our analyses demonstrate a lack of genetic structure for COI among the Atlantic and East Pacific populations of M. similis , including the Bering Sea population corresponding to M. asiatica , therefore there is no molecular evidence for considering these as two separate taxa ( Fig. 2 , 4 b ). We found morphological variation at the individual level among and within the Atlantic and East Pacific populations in the relative width of the rostrum in relation to length, the presence or absence of a dorsal carina and the presence or absence of small additional spines on the epigastric and hepatic dorsal carapace (see Supplementary Fig. S8 ). Variations within these characters were considered to be morphological differences between both species ( Marin 2020). However, when several specimens of different populations are examined, this variation becomes intraspecific. Therefore, due to the lack of morphological and molecular support, we propose M. asiatica as a junior synonym of M. similis .

Figures

Fig. 8. (a–g) Line diagrams of Munidopsis carinipes Faxon, 1893, M 10.09 mm, lectotype (MCZ IZ CRU-4561), Panama. (h–n) Line diagrams of Munidopsis quadrata Faxon, 1893 M 9.8 mm, lectotype (MCZ IZ CRU-4560), Mexico. (a, g) Carapace and abdomen, dorsal view. (b, i) Cephalic region, showing antennular and antennal peduncles, ventral view. (c, j) P1, dorsal view. (d, k) Left P2, lateral view. (e, l) Left P3, lateral view. (f, m) Left P4, lateral view. (g, n) Left P2 dactyl. Scale bars: 1 mm.

Fig. 18. Munidopsis similis Smith, 1885. (a, d) Holotype, Nantucket Shoals, Northwest Atlantic (USNM 8255). (b, e) Gay Head–Bermuda transect, Northwest Atlantic (MCZ IZ-81478). (c, f) California, East Pacific (MCZ IZ-162084). Scale bars: a, b, 2 mm; c–f, 1 mm.

Fig. 2. Phylogenetic hypotheses based on the COI data alone resulting from the Bayesian analysis, with results from the species delimitation analyses (ASAP, ABGD, bPTP, GMYC); a grey box indicates that the specimens are not part of the species hypothesis of the black bar. Tip labels in bold indicate new taxa. Colours indicate geographic distribution as specified on the map. Gradients of depth and habitat are also indicated. Asterisks indicate supported nodes: ML bootstrap support>70%/Bayesian posterior probability>0.95.

Fig. 4. Haplotype networks with haplotype distributions for (a) Munidopsis piipa + M. kexuae and (b) M. similis + M. asiatica.