Munidopsis girguisi, Rodríguez-Flores & Seid & Rouse & Giribet, 2023

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 : 29-34

Munidopsis girguisi sp. nov.

( Fig. 9 a–k , 10 a, b, g , 11 a, d , Supplementary Fig. S3 .)

ZooBank: urn:lsid:zoobank.org:act:5FAD0D92-72A1-492E-B4D0-B2AB AD807F70

Material examined

Holotype. USA: California, leg. E/V Nautilus , ROV Hercules dive H1455, Stn NA066-152, 8.viii.2015, 33.66222°N, 118.56974°W, 535 m: 1 M 18 mm ( MCZ IZ-73856 ).

Paratypes. Same collecting data as holotype: 1 M 4 mm, 1 F 10 mm ( MCZ IZ-163059 ). — USA: California, leg. E/V Nautilus , ROV Hercules dive H1455, Stn NA066-145, 8.viii.2015, 33.66009°N, 118.57134°W, 558 m: 1 F broken 7 mm ( MCZ IZ-73852 ). — USA: Point Dume , off Malibu , California, leg. Charlotte Seid, Emily McLaughlin, R/V Falkor, ROV SuBastian dive S0163, Slurp 1, 8.x.2018, 33.94187°N, 118.84381°W, 719 m: 14 M 11.6–16.7 mm, 4 ov. F 12.3–15.6 mm, 3 F 9.9–11.2 mm (ethanol-treated specimens, SIO-BIC C14008 ), 4 M 16.6–20.0 mm 2 ov. F 12.3–13.4 mm (formalin-fixed specimens, SIO-BIC C14008 ).

Non-type specimens. USA: California, leg. E/V Nautilus, ROV Hercules dive H1455, Stn NA066-151, 8.viii.2015, 33.66017°N, 118.56964°W, 554.6 m: 1 M 3 mm, 1 F 4.7 mm (MCZ IZ-73844). — USA: California: seep, leg. E/V Nautilus, ROV Hercules dive H1455, Stn NA066-150, 8.viii.2015, 33.6604°N, 118.5695°W, 554 m: 1 M 4.5 mm, 1 F 2.0 mm (broken) (MCZ IZ-74029). — USA: Point Dume, off Malibu, California, leg. Charlotte Seid, Emily McLaughlin, R/V Falkor, ROV SuBastian dive S0164, Slurp 4, 9.x.2018, 33.94186°N, 118.843986°W, 723 m, 1 ov. F 12.3 mm (SIO-BIC C14010). — USA: Point Dume, off Malibu, California, leg. Charlotte Seid, Emily McLaughlin, R/V Falkor, ROV SuBastian dive S0164, Slurp 3, 9.x.2018, 33.94187°N, 118.84376°W, 723 m, 2 M 14.5–15.6 mm (formalin-fixed specimens, SIO-BIC C14012), 5 M 12.3–15.6 mm, 1 ov. F 13.4 mm, 1 F 12.3 mm (ethanol-treated specimens, SIO-BIC C14012). — USA: Redondo Knoll, off California, leg. Charlotte Seid, Emily McLaughlin, R/V Falkor, ROV SuBastian dive S0167, 11.x.2018, 33.68120°N, 118.57140°W to 33.6898°N, 118.57497°W), 498–578 m: 1 F 6.7 mm (SIO-BIC C14038). — USA: Santa Monica Mound and Fossil Hill, off California, leg. Greg Rouse, R/V Western Flyer, ROV Doc Ricketts dive D1250, 7.ii.2020, 33.83851°N, 118.69038°W to 33.84447°N, 118.68830W, 623–863 m, 1 M 16.7 mm (SIO-BIC C14442), 1 M 12.3 mm 3 ov. F 11.2–14.5 mm (SIO-BIC C14443). — USA: Santa Monica Mound, off California, leg. Greg Rouse, R/V Western Flyer, ROV Doc Ricketts dive D1252, 8.ii.2020, 33.79938°N, 118.64631°W to 33.79947°N, 118.64698°W, 789–807 m, 1 ov. F 10.0 mm (SIO-BIC C14445). — USA: Lasuen Knoll, off California, leg. Greg Rouse, Nicolas Mongiardino Koch, R/V Falkor, ROV SuBastian dive S0449, SCB-236, slurp 2, 2.viii.2021, 33.38816°N, 118.00555°W, 382 m, 1 M 13.4 mm (SIO-BIC C14553). — USA: Lasuen Knoll, off California, leg. Greg Rouse, Nicolas Mongiardino Koch, R/V Falkor, ROV SuBastian dive S0449, SCB-235, 2.viii.2021, 33.38818°N, 118.00556°W, 382 m, 2 F 9.9–8.8 mm (SIO-BIC C14554). — USA: Rosebud whalefall, off San Diego, California, leg. Greg Rouse, R/V Western Flyer, ROV Doc Ricketts dive D1253, 9.ii.2020, 32.77687°N, 117.48807°W, 845 m: 1 M 13.4 mm (SIO-BIC C14437). — USA: California, leg. Robert C. Vrijenhoek, R /V Western Flyer, ROV Doc Ricketts dive D476, 21.v.2013, 33.843400°N, 118.68900°W, 664 m, 6 M 5.4–10.8 mm, 3 ov. F 11.5–12.3 mm, 4 F 7.0–11.4 mm (USNM 1463927). — USA: California, leg. Robert C. Vrijenhoek, R /V Western Flyer, ROV Doc Ricketts dive D631, 24.vi.2014, 33.90430°N, 118.73400°W, 535 m, 2 M 3.1–4.0 m, 2 F 3.7–12.5 mm (USNM 1487201), 2 M 3.1–3.3 mm, 2 F 3.3–5.7 mm (USNM 1487195).

COSTA RICA: Jaco Summit, leg. Greg Rouse, Allison Miller, R/V Falkor, ROV SuBastian dive S0213, 6.i.2019, 9.17341°N, 84.80380°W, 730–820 m: 2 specimens not measured (tissue SIO-BIC C13897 ex MZUCR 3760-01).

Etymology

Named for Prof. Peter Girguis, Chief Scientist of the R/V Falkor ‘Backyard Deep’ cruise FK181005, during which most of the paratypes were collected. The type locality off Los Angeles matches Prof. Girguis’ ‘Angeleno’ origins. The presence of filamentous bacteria resonates with Prof. Girguis’ research in deep-sea microbiology, and the tripoint carapace marking resembles the ABISS autonomous lander deployed by the Girguis lab on this cruise. We honor Prof. Girguis’ enthusiasm for collecting these animals and his kind, inclusive leadership as Chief Scientist.

Diagnosis

Carapace quadrangular, dorsally smooth, with pair of epigastric scales, with dorsal deep furrows and rugae, cervical grooves indistinct. Rostrum broadly triangular, lateral margins convergent, unarmed. Frontal margins slightly oblique. Orbit not distinctly excavated, outer orbital angle with a minute spine. Anterolateral angle armed with a small spine. Branchial margin serrated, unarmed. Pterygostomian flap with rugae. Abdominal somites unarmed. Telson divided into 7–8 plates. Sternite 3 anterolaterally rounded, anterior margin with median notch flanked by 2 lobes, sternite 4 subtriangular. Eyes unarmed, movable, epistomial spine present. Article 1 of antennule with dorsolateral process mesially concave. Article 1 of antenna with well-developed distolateral spine. Mxp3 merus subrhomboidal in lateral view. P1 moderately stout, with some spines, fixed finger without denticulate carina on distolateral margin. P2–4 stout, unarmed; meri carinated, propodi paddle-shaped; dactyli stout, curving, flexor margin with cuticular teeth along all margin decreasing proximally. Epipods absent from all pereopods.

Description

Carapace

Quadrangular, slightly longer than broad, widest at posterior part; slightly convex from side to side. Dorsal surface smooth, with two epigastric produced scales, hepatic and anterior branchial areas with scarce rugae; posterior cardiac and intestinal region with few rugae. Regions well delineated by deep furrows, anterior and posterior cervical grooves indistinct. Gastric region slightly elevated. Posterior cardiac region constricted by lateral furrows, forming notches; posterior margin unarmed, preceded by deep transverse depression. Rostrum broadly triangular, dorsally concave, width 0.15–0.25× anterior width of carapace, horizontal, lateral margins coarsely serrated, ventrally convex and carinated, 0.2–0.3× carapace length, 1–1.5× as long as broad. Frontal margin serrated, oblique behind ocular peduncle, blunt outer orbital angle above antennal peduncle, outer orbital spine and process (antennal spine) minute. Lateral margins carinated, with numerous rugae, preceded by a depression, nearly straight proximally, oblique distally; anterolateral spine minute. Pterygostomian flap surface with large and short rugae, anteriorly acute.

Sternum

Slightly longer than broad, maximum width at sternite 6. Sternite 3 moderately broad, 1.8–2.5× wider than long, anterolaterally rounded, anterior margin with median notch flanked by 2 lobes. Sternite 4 narrowly elongate anteriorly; surface depressed in midline, smooth; greatest width 2–3× that of sternite 3 and 2.0× wider than long.

Abdomen

Unarmed; tergite 2 with 2 elevated transverse ridges, smooth; tergites 3–5 lacking posterior ridge; tergite 6 with weakly produced posterolateral lobes and nearly transverse posteromedian margin. Telson composed of 7–8 plates, 1.2× as wide as long.

Eye

Eyestalk movable, partially concealed by rostrum; peduncle smooth, longer than cornea length; cornea subglobular; lateral surface contiguous to epistomial spine, ventral to frontal margin.

Antennule

Article 1 of peduncle with dorsolateral process mesially concave, distally serrated; distomesial margin produced and squamate.

Antenna

Peduncle not exceeding eye; article 1 with strong distolateral spine, distomesial angle unarmed, not reaching end of article 2, partially concealed by pterygostomian flap. Article 2 with well-developed distomesial and distolateral spines. Article 3 longer than article 2, with well-developed distomesial and distolateral spines, often double distolateral or distomesial spines. Article 4 unarmed. Flagellum longer than carapace.

Mxp3

Surface smooth. Flexor margin of merus with 2 spines, proximal larger, small distal spine; extensor margin with 1 distal spine. Ischium slightly longer than merus measured on extensor margin, unarmed. Crista dentate, finely denticulate. Dactylus, propodus and carpus unarmed.

P1

Moderately stout, with some granules and scales, females 1.7–1.9, males 1.8–2.2× longer than carapace. Merus 1.9–2.0× carpus length, with some spines at all surfaces, mesial stronger, including a few distal stout spines, dorsal margin proximally carinated. Carpus 1.5–1.8× longer than broad, with few spines at all surfaces, distal spines absent. Palm stout, slightly longer than carpus, 1.5–1.7× longer than broad, with row of small spines on mesial and lateral margins. Fingers unarmed, 0.7–0.9× longer than palm, opposable margins nearly straight, slightly gaping, spooned; fixed finger without denticulate carina on distolateral margin.

P2–4

Stout, coarsely granulated, devoid of setae, slightly decreasing in size posteriorly. P2 merus stout, 0.3–0.5× carapace length, nearly 3.0× longer than high and 1.1–1.2× length of P2 propodus. P2–4 meri decreasing in length posteriorly (P3 merus 0.8 length of P2 merus, P4 merus 0.9 length of P3 merus); extensor margin of P2–4 meri carinated, with small spines along entire bor-der, distal part flattish ending in thick spine; flexor margin granulate ending in a thick spine; carpi with one small spine on extensor margin, granulated carina along lateral side; P2–4 propodi paddle-shaped, 2.6–2.7× as long as high, flattened in cross-section, extensor margin granulated; dactyli 0.6–0.7× length of propodi; distal claw short, moderately curved; flexor margin distally curved, with 11–13 min dactylar teeth decreasing in size proximally, each with slender corneous spine, ultimate tooth closer to dactylar angle than to penultimate tooth.

Epipods

Absent from pereopods.

Eggs

Approximately 10–45 eggs, 0.6–1 mm in diameter.

Colouration

Carapace and pereopods pink or varying shades of orange; carapace with a white tripoint marking on many of the California specimens.

Distribution

California and Costa Rica from 381- to 845-m depth.

Genetic data

COI, 16S rRNA and 28S rRNA.

Remarks

This new species appears to be covered by filamentous bacteria on the carapace, abdomen and chelipeds when alive but these bacteria were missing after fixation. Other squat lobster species living in hydrothermal vents and cold seeps exhibit this kind of epibiotic bacteria (e.g. Goffredi et al. 2008). Munidopsis girguisi sp. nov. resembles Munidopsis denudata Macpherson, 2007 from the Solomon Islands and M. inermis Faxon, 1893 from Panama. However, the new species is easily distinguished from these species by the following characters:

• The new species has deep furrows on the dorsal surface of the carapace and rugae on the pterygostomian flap, whereas these surfaces are smooth in M. denudata and in M. inermis .

• The frontal margin of the carapace is unarmed in M. denudata and M. inermis whereas this is armed with a minute antennal spine in the new species.

• The anterolateral angle is unarmed in M. denudata and M. inermis whereas this angle is armed with a small spine in the new species.

• The new species has an acute triangular rostrum whereas M. denudata has a broadly triangular rostrum.

• The flexor margin of the Mxp3 is armed with one strong proximal spine and one small distal spine in M. denudata whereas this margin is armed with two proximal spines in the new species.

• P1–4 have spines in the new species, whereas these are unarmed in M. denudata and M. inermis .

• The dactyli flexor margin is unamred in Munidopsis inermis whereas this margin is armed with minute spines in the new species.

Figures

Fig. 9. Line diagrams of Munidopsis girguisi sp. nov., M 18 mm, holotype (MCZ IZ-73856), California. (a) Carapace and abdomen, dorsal view. (b) Carapace and abdomen, lateral view. (c) Sternal plastron. (d) Telson. (e) Cephalic region, showing antennular and antennal peduncles, ventral view. (f) Left Mxp3, lateral view. (g) Left P1, dorsal view. (h) Right P2, lateral view. (i) Right P3, lateral view. (j) Right P4, lateral view. (k) Right P3 dactyli, lateral view. Scale bars: 1 mm.

Fig. 10. In situ images. (a, b) Munidopsis girguisi sp. nov., California, dive S0449, SCB-236 (SIO- BIC C14553). (c, d) Munidopsis hendrickxi sp. nov., California, Stn NA117-012-01-B-MCZ, holotype (MCZ IZ-153106). (e, f) Munidopsis similis Smith, 1885, Costa Rica, dive S0230 S3 (SIO-BIC C13964). (g–h) Costa Rica, dive S0213. (g) Munidopsis girguisi sp. nov. (SIO-BIC C13897). (h) Munidopsis cortesi sp. nov., holotype (MZUCR 3761-01). Photo credits: ROV SuBastian/ Schmidt Ocean Institute (a, b, e–h) and Nautilus Live Ocean Exploration Trust (c, d).

Fig. 11. Three-dimensional renderings of Micro-computed tomography X-ray images. (a, d) Munidopsis girguisi sp. nov., M 18 mm, holotype (MCZ IZ-73856). (b, e) Munidopsis hendrickxi sp. nov., M 9.1 mm, holotype (MCZ IZ-153106). (c, e) Munidopsis cortesi sp. nov., ov. F 5.2 mm, holotype (MZUCR 3761-01). Three-dimensional reconstructions available from MCZbase.

Fig. 3. Haplotype networks with haplotype distributions for (a) Munidopsis aspera and (b) M. quadrata + M. carinipes.