Three new American species of Munidopsis ( Crustacea : Anomura : Munidopsidae )

Three new species of Munidopsis (M. amapa and M. brasilia from Brazil, and M. bajacalifornia from California and the Galápagos Islands) are described. All are small, superficially similar to each other and from shallower depths than is typical of most of the genus. All species have a highly sculptured carapace, triangular rostrum and immovable eyestalks with prominent anterior


INTRODUCTION
Collections of squat lobsters in museums in the USA and Brazil were surveyed as a contribution to Museum Victoria's Mapping the World's Oceans project (part of INDEEP, International network for Scientific investigation of deepsea ecosystems http://www.indeep-project.org/wg/global-biodiversity-biogeography).Several specimens belonging to three new species of Munidopsis were uncovered.Munidopsis comprises more than 230 accepted described species, about two-thirds from the Indo-West Pacific (Baba et al., 2008;WoRMS Editorial Board, 2014).About two-thirds of all species are found at depths below 1000 m (Baeza, 2011).The three new species are small, superficially similar to each other, and all are from shallower depths that is typical of most of the genus; two are from the Southwestern Atlantic and the other from the Central-eastern Pacific.In this contribution the three species are described.The discussion that follows the descriptions examines their similarities to each other and to other species.
Pereopods 1-3 with epipod.Distribution: Northern Brazil, 101 m depth.Etymology: From Amapá, the state of Brazil close to the type locality, noun in apposition.Remarks: The maximum total length recorded is 5.2 mm as is the case for all three species.Neither of the types possesses pereopods but these are assumed to be similar to those of the next species, M. bajacalifornia with which it is compared below.Eyestalk immovable, sparsely setose, with prominent distomesial lobe adpressed along two-thirds of side of rostrum, denticulate laterally; with strong oblique conical distodorsal and shorter distoventral projections reaching little more than half rostrum length.Cornea hemispherical, lateral, occupying proximal two-thirds of eyestalk.

Munidopsis bajacalifornia
Antennule article 1 swollen, with obsolete distomesial spine, distoventral spine about as long as body of article and shorter distodorsal process.
Antenna article 1 with short sharp lateral tooth; article 2 with lateral spine reaching distal margin of article 3; article 3 with short lateral spine; article 4 unarmed.
Pereopods 1-3 with epipod.Distribution: Baja California, Mexico, and Galapagos Islands, Ecuador, 28°N -04°S, 101-174 m depth.Etymology: From Baja California, a state of Mexico, for the type locality; noun in apposition.Remarks: This like the others is a small species, 5.2 mm being the maximum total length recorded.The combination of squamose teeth on the carapace and acute lateral eyespines on an immovable eyestalk distinguish it from A. amapa, which has more complex dorsal ornamentation and shorter more rounded lateral eyespines.
Eyestalk immovable, deeper than wide, with short blunt dorsolateral spine, and short conical ventrolateral and ventromesial teeth on lower distal margin.
Antennule article 1 swollen, with distolateral and subdistal mesial spines shorter than body of article, plus minute mesial tooth.
Pereopod 1 (cheliped) equal, 1.1 times carapace length; surfaces largely smooth; merus 3 times as long as carpus, upper edge with 1+1 mesial, 1+1 in midline, 1 intermediate and 6+1 lateral spines, lateral face with distal spine; lower margin unarmed; carpus upper edge with 2 proximal + 1 blunt teeth, lateral face with 3+1 teeth, lower margin with 1 spine; propodal palm as long as dactylus, length 2.3 times height, upper edge with 4 irregular teeth, lower margin squamose; fixed finger with sharp blade-like irregular outer margin, with irregular sharp obtuse distal teeth, mesial margin rounded, upper surface concave; dactylus with sharp blade-like outer margin, with semicircular apex about as long as fixed finger, mesial margin rounded.
Pereopods 1-3 with epipod.Distribution: Northern to central Brazil, 4°N -22°S, 65-118 m depth.Etymology: From Brasilia (Latinised spelling of Brazil), reflecting the species' distribution, noun in apposition.Remarks: This is a small species, 5 mm being the maximum total length recorded.The combination of well-spaced blunt but definite teeth on the carapace and lateral eyespines on an immovable eyestalk are diagnostic.

DISCUSSION
Munidopsis is a genus with six junior synonyms that reflect its morphological diversity.A generic revision using morphological and molecular data is underway (S.Ahyong, J. Taylor, N. Andreakis, pers.comm.)so it would be presumptuous to pre-empt this and place the new species in any genus other than Munidopsis.Nevertheless, a superficial review of the type species of these junior synonyms does not reveal a stand-out existing genus name in which to place the new species.
The three species, all from inner-or mid-shelf depths, have in common small size (none much more than 5 mm long), broad triangular rostrum, eyestalk immovable, with distal eyespines, ornamented dorsal sculpture, and epipods on pereopods 1-3.Twenty-seven species of Munidopsis were listed from the Eastern Pacific by Hendrickx and Harvey (1999), with more recent additions from the Gulf of California (Ayón-Parente and Hendrickx, 2007;Hendrickx, 2007;Hendrickx and Ayón-Parente, 2013).Studies of the fauna of the Gulf of Mexico are relevant to the Brazilian fauna (Pequegnat and Pequegnat, 1970;Pequegnat and Williams, 1995;Váquez-Bader et al., 2014) but only two species of Munidopsis have been reported from Brazil itself (Melo, 1999).All the species covered in these studies are from outer shelf or bathyal depths; none is similar to the new species described here.
Munidopsis bajacalifornia and M. amapa are more similar to each other than they are to M. brasilia.Both share complex dorsal tubercles on the carapace (notably a stout pair of epigastric tubercles and a pair of protruding hepatic shoulders overlapping the anterolateral carapace margin), a lateral rostral constriction, a prominent anterior lobe on sternite 4, two lateral projections on the eyestalks arranged one above the other, and two lateral spines on article 1 of the antennule.Pereopods are known only for the first of these two.The eyespines on M. amapa are more blunt and the rostrum longer and more horizontal than in M. bajacalifornia.
Munidopsis brasilia has dorsal carapace spines rather than complex squamae but shares two lateral eyespines, one above the other, and a spinose merus and carpus on pereopod 1 with the other two species.Sternite 3 is narrower than in the other two species.
Listing just the most obvious differences of described species from these new American ones, Munidopsis bractea, M. papanui, M. taurulus and M. tuberosa have more prominent ridges on the abdominal somites and complex antennular spines, M. tasmaniae has more prominent lateral hepatic and anterior branchial tubercles, and M. proales, M. tasmaniae, M. sonne and M. tuberosa lack prominent eyespines and are less sculptured.
Whether or not these three species form a natural group within Munidopsis sensu lato remains to be seen.