Cosmopolitan abyssal lineages? A systematic study of East Pacific deep-sea squat lobsters (Decapoda: Galatheoidea: Munidopsidae) Author Rodríguez-Flores, Paula C. Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA. paularodriguezflores@g.harvard.edu Author Seid, Charlotte A. Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA. Author Rouse, Greg W. Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA. Author Giribet, Gonzalo Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA. text Invertebrate Systematics 2023 2023-01-11 37 1 14 60 http://dx.doi.org/10.1071/is22030 journal article 10.1071/is22030 83c35eac-4bc8-40c5-a8f0-a19ef107d792 7534735 Munidopsis aspera ( Henderson, 1885 ) ( Fig. 6 a–j , 7 a–e , Supplementary Fig. S1 .) Elasmonotus asper Henderson, 1885 Munidopsis townsendi Benedict, 1902 , syn. nov. Munidopsis alfredolaguardai Hendrickx & Ayón-Parente, 2013 , syn. nov. Material examined Holotype ( M. townsendi ). ECUADOR : Galapagos Islands , Santa Cruz and San Cristobal Islands , leg. USFC Steamer Albatross , Stn 2818, field number USFC/A2818, 0.48330°S , 89.90830°W , 15.iv.1888 , 717 m : ov. F 8.1 mm ( USNM 26167 ). Non-type specimens . Magellan Strait, A. Milne-Edwards det., Saint Laurent re-det.: 2 ov. F 10.2–10.9 mm (MNHN Ga301). Magellan Strait, leg. Nerida Wilson, Greg Rouse, R/V Nathaniel Palmer , Stn SM1b-3, 10.iv.2013, 53.6022°S, 70.2456°W to 53.6025°S, 70.2322°W, 270–285 m: 1 M 13.4 mm, 1 ov. F 12.3 mm (SIO-BIC C11873). ECUADOR: east of Galapagos Islands, leg. USFC Steamer Albatross , Stn 3402, 28.iii.1891, 0.95833°S, 89.05833°W, 421 fms (769.9 m): 1 M 6.5 mm, 3 ov. F 7.5–7.8 mm, 2 F 7.5–8.3 mm (MCZ IZ CRU-4557). — ECUADOR: east of San Salvador Island, Galapagos Islands, leg. USFC Steamer Albatross , Stn 3406, 3.iii.1891, 0.26666°S, 90.35833°W, 551 fms (1008 m): 1 M 4.8 mm, 1 F 5.1 mm (MCZ IZ CRU-4558). COSTA RICA: The Thumb, leg. Greg Rouse, Allison Miller, R/V Falkor , ROV SuBastian dive S0217 B4-3, 10.i.2019, 9.04915°N, 84.39308°W, 1065 m; specimen not measured (SIO-BIC C13912), juvenile (SIO-BIC C13913). — COSTA RICA: Seamount 8, leg. Greg Rouse, Avery Hiley, R/V Falkor , ROV SuBastian dive S0226 Q7, 21.i.2019, 6.00765°N, 86.64906°W, 1310 m: 1 ov. F 11.2 mm (SIO-BIC C13951). MEXICO: Guaymas Basin, Gulf of California, leg. Greg Rouse, Sigrid Katz, R/V Western Flyer , ROV Doc Ricketts dive D381, 11.iv.2012, 27.89591°N, 111.96700°W, 1064 m: 1 M 8.8 mm (SIO-BIC C14144) . USA: Pioneer Seamount, off San Francisco, California, leg. Craig McClain, David Clague, R/V Western Flyer , ROV Tiburon dive T1100, 18.vi.2006, 37.36141°N, 123.39300°W, 1229–1513 m: 1 M 6.75 mm (SIO- BIC C11953). — USA: off San Diego, California, leg. Greg Rouse and students, R/V Robert Gordon Sproul , otter trawl within oxygen minimum zone, 5.viii.2017, 32.7553°N, 117.4546°W, 570 m: 1 M 11.2 mm (SIO-BIC C12687), 1 ov. F 10.1 mm (SIO-BIC C12688), 1 M 11.2 mm (SIO-BIC C12524). — USA: off San Diego, California, leg. Greg Rouse, Avery Hiley and students, R/V Robert Gordon Sproul , SP1825 , Stn 3 otter trawl, 2.ix.2018, 32.76463°N, 117.45417°W to 32.77180°N, 117.45325°W, 500 m: 1 ov. F 11.1 mm (SIO-BIC C13703). — USA: off San Diego, California, leg. Gabriella Berman, Sonja Huc, R/V Robert Gordon Sproul , SP2115 otter trawl, 7.viii.2021, 32.73467°N, 117.45100°W to 32.80017°N, 117.41567°W, 500 m: 1 ov. F 10 mm (SIO-BIC C14526). Description Carapace Slightly longer than broad, widest at midlength; convex from side to side. Dorsal surface densely covered by acute denticles and denticulated tubercles, each denticle or tubercle with few short setae, hepatic and anterior branchial areas with denticles and some acute denticles. Regions well delineated by deep furrows, anterior and posterior cervical grooves distinct. Gastric region flattened. Posterior margin armed with tubercles, preceded by elevated ridge. Rostrum triangular to spiniform, setose, width 0.2–0.3× anterior width of carapace, directed slightly upwards, denticles and tubercles on margin and dorsal surface, 0.3× carapace length, 1.3–1.6× as long as broad. Frontal margin slightly concave behind ocular peduncle, blunt outer orbital angle above antennal peduncle, orbit delimited by several outer orbital denticles or tubercles. Lateral margins convex; anterolateral angle armed with acute tubercles; branchial margins, tuberculated, denticulated. Pterygostomian flap surface covered by denticles and granules, anterior margin blunt. Fig. 6. Line drawings of Munidopsis aspera Henderson, 1885 , ov. F 10.9 mm (MNHN-Ga301), Magellan Strait. ( 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 ) Right Mxp3, lateral view. ( g ) Left P1, dorsal view. ( h ) Left P2, lateral view. ( i ) Left (unattached) P4, lateral view. ( j ) Left P2 dactyli. Scale bars: 1 mm. Fig. 7. Munidopsis townsendi Benedict, 1902 , Galapagos, holotype (USNM 26167). ( a ) Carapace and abdomen, dorsal view. ( b ) Anterior carapace and rostrum, dorsal view. ( c ) Telson. ( d ) Sternal plastron. ( e ) Unattached leg dactyli. Scale bars: 1 mm. Sternum Slightly longer than broad, maximum width at sternite 6. Sternite 3 broad, 2.2–2.6× wider than long, anterolaterally rounded, often serrated, anterior margin with median notch flanked by 2 lobes. Sternite 4 narrowly elongate anteriorly, anterior margin smooth; surface depressed in midline, smooth; greatest width 2.5–3.2× that of sternite 3, and 2.0–2.7× wider than long. Abdomen Tergites with tubercles and denticles in all surfaces, tergites 2–4 armed with a median broad spine covered by tubercles, tergites 2–3 with 1 elevated transverse ridge; tergites 4–6 lacking ridges; tergite 6 with weakly developed posterolateral lobes and nearly transverse posteromedian margin. Telson composed of 9 plates; 1.4–1.5× as wide as long. Eye Eyestalk movable; peduncle elongated, densely covered by denticles and small tubercles, narrower than cornea length; cornea ovoid, length 0.7–0.9× that of peduncle; epistomial spine (below antennal spine, ventral to frontal margin) absent. Antennule Article 1 of peduncle with subequal dorsolateral and distolateral spines, distolateral margin proximally armed with denticles; distomesial margin with denticles. Antenna Peduncle not exceeding eye, armed with denticles and granules; article 1 with distomesial spine and distolateral spine, distomesial spine reaching end of article 2. Article 2 unarmed or with minute distomesial and distolateral spine. Article 3 unarmed or with small lateral spine or with prominent distal denticles; article 4 unarmed. Mxp3 Surface with granules and denticles. Ischium 1.3× longer than merus measured on extensor margin, distal margin serrated; flexor margin of merus with one prominent spine and several denticles, extensor margin with 3–4 spines including distal spine. P1 Moderately slender, females 1.7–2.0, males 2.5–2.7× longer than carapace, cylindrical, with numerous tubercles and denticles. Merus 2.4–2.8× carpus length, with denticles and spines on all surfaces. Carpus 1.3–1.5× longer than broad, unarmed or with rows of spines on mesial, lateral margins and some distal stout spines. Palm with row of spines on all surfaces, moderately slender, 2.6× longer than carpus, 2.6–2.8× longer than broad. Fingers unarmed or armed with proximal small spines or denticles, 0.7–0.9× longer than palm, opposable margins nearly straight, not gaping, spoon-shaped; fixed finger without denticulate carina on distolateral margin. P2–4 Moderately slender, coarsely tuberculated and denticulated in all surfaces, with fine distally curved setae on meri and carpi, cylindrical in cross section, slightly decreasing in size posteriorly. P2 merus moderately slender, 0.5–0.6× carapace length, nearly 4.0× longer than high and 1.5× length of P2 propodus. P2–4 meri decreasing in length posteriorly (P3 merus 0.9× length of P2 merus, P4 merus 0.9× length of P3 merus); extensor margin with granules and denticles along entire border, distal part cylindrical ending in 1–2 thick spines; flexor margin tuberculated; P2–4 carpi with 0–3 thick spines on extensor margin, acute tubercles on lateral sides; P2–4 propodi with acute tubercles on extensor margin and lateral sides, distal flattened, ending in 3 denticles, 5.2–6.0× as long as high, flattened in cross section, unarmed; dactyli short, 0.4–0.5× length of propodi; distal claw short, moderately curved; flexor margin distally strongly curved, unarmed. Epipods Absent from pereopods. Eggs Approximately 10–55 round eggs of 1 mm each. Colouration Body and pereopods whitish to light brownish, with light orange eyes. Distribution California, Gulf of California, to Strait of Magellan, from 166- to 1398-m depth. Genetic data COI , 16S rRNA and 28S rRNA. Remarks Munidopsis aspera was described from Port Churruca, Magellan strait, Chile ( Henderson 1885 ), with additional records from Galapagos (Ecuador), Cocos Islands (Costa Rica) ( Faxon 1895 ) and California ( Schmitt 1921 ; Luke 1977 ). The species was poorly illustrated in the literature ( Wicksten 2012 ) but considered widely distributed across the East Pacific ( Baba et al. 2008 ). Munidopsis townsendi Benedict, 1902 was described from Galapagos and only the anterior part of the carapace and rostrum, and the left P1 were illustrated ( Benedict 1902 ). Munidopsis alfredolaguardai was described from the Baja California Peninsula in the SW Gulf of California ( Hendrickx and Ayón-Parente 2013 ) and later recorded from Chile ( Guzman and Sellanes 2015 ). Munidopsis alfredolaguardai , M. aspera and M. townsendi are similar morphologically but undertaking a definitive comparison among species was difficult because of the absence of proper illustrations of M. aspera and M. townsendi . We analysed the morphology and genetics from material from the full range of M. aspera , including material from the type locality (Magellan Strait), Galapagos and Gulf of California, and the type of M. townsendi . We found morphological variation among specimens across the range of the species in carapace size, spinulation on cheliped palms, the number and size of the external denticles and tubercles on carapace, pereiopods, ocular peduncles and antennal articles. However, we did not elucidate genetic structure genetic differences across the distribution range for all the markers analysed ( Fig. 1–3 a ), nor morphological differences between M. aspera and M. townsendi and an illustrated description of M. alfredolaguardai (Hendrickx and AyónParente 2013; Guzman and Sellanes 2015 ). We therefore conclude that M. alfredolaguardai and M. townsendi are junior synonyms of M. aspera . Munidopsis aspera belongs to a group of species sharing a frontal margin without delimited orbit, telson with 9–10 plates, eye movable, unarmed, with peduncle longer than cornea and epipods absent from all pereiopods. This group of species includes M. quadrata and M. carinipes from the Northern East Pacific, M. longimanus from the Gulf of Mexico and the Caribbean Sea, M. robusta from the Caribbean Sea, M. depressa from California, M. abdominalis (A. Milne Edwards, 1880) from the Caribbean Sea, M. alaminos Pequegnat & Pequegnat, 1970 from the Gulf of Mexico, M. brevimana (A. Milne Edwards, 1880) from the Caribbean Sea and M. riveroi Chace, 1939 from the Gulf of Mexico and the Caribbean Sea. Munidopsis aspera is easily distinguished from the remaining species of the group by having the flexor margin of the dactyli unarmed, and the carapace, pereopods, ocular peduncles and antennal articles densely covered by denticles and tubercles.