Munida grossetana, Garassino & Pasini, 2015

Garassino, Alessandro & Pasini, Giovanni, 2015, A new squat lobster (Crustacea, Anomura, Munididae) from the Pliocene of Monterotondo Marittimo (Tuscany, Italy), Natural History Sciences 2 (1), pp. 39-41 : 40-41

Munida grossetana n. sp.

Fig. 1

Etymology: The trivial name alludes to Grosseto, regional capital where the fossiliferous locality is located.

Holotype: MSNM i28256.

Paratype: MSNM i28257.

Type locality: Monterotondo Marittimo (Grosseto, Tuscany, Italy) .

Geological age: Pliocene sensu lato.

Material and measurements: Two complete carapaces (one without rostrum). MSNM i28256 – lcxp: 5 mm; lr: 2 mm; wcxp: 5 mm; MSNM i28257 – lcxp: 4 mm; wcxp: 4 mm.

Diagnosis: Carapace (excluding rostrum) as long as wide; rostrum slender and spiniform; carapace with transverse striae well spaced; gastric region without epigastric spines; anterolateral margin with one spine; branchial and posterolateral margins smooth.

Description: Carapace (excluding rostrum) as long as wide, slightly convex laterally; dorsal striae and cervical groove well distinct; gastric region convex and without epigastric spines; epigastric, hepatic, cardiac, intestinal, and branchial regions spineless; all regions with entire transverse striae well spaced, with very few secondary striae; anterior and posterior cervical groove deep; rostrum elongate, dorsally ridged, laterally armed with three spines; supraocular spine small, subparallel, close to rostrum; anterolateral margin with one small anterolateral spine situated at anterolateral angle, not reaching level of sinus between rostrum and supraocular spine; branchial and posterolateral margins smooth.

Discussion: According to Poore (2004) the studied specimens are assigned to the fossil and extant Munida in having carapace with distinct transverse striae, slen- der spiniform rostrum, and frontal margin of carapace without spine mesiad to anterolateral spine. The studied specimens are further assigned to Munididae Ahyong, Baba, MacPherson & Poore, 2010 , for having a slender spiniform rostrum and for the presence of the supraocular spines. Previously Munida was assigned to Galatheidae Samouelle, 1819 , by Schweitzer et al. (2010). However, based upon the recent classification proposed by Ahyong et al. (2010), this genus fits better within the Munididae . Schweitzer et al. (2010) assigned five fossil species to Munida : M. konara Schweitzer & Feldmann, 2000 , from the late Oligocene - early Miocene of Alaska; M. nishioi Karasawa, 1993 , from the middle Eocene of Japan; M. ogaensis ( Hatai & Kotaka, 1970) from the middle-late Miocene of Japan; M. primaeva Segerberg, 1900 , from the Danian of Denmark; M. quadroblonga Schweitzer & Feldmann, 2000 , from the Eocene of Bainbridge Island (WA, United States) ( Segerberg, 1900; Hatai & Kotaka, 1970; Karasawa, 1993; Schweitzer & Feldmann, 2000).

Based on the main characters of the above-mentioned species, we justify the description of Munida grossetana n. sp. for the rostrum, slender and spiniform with three lateral spines, for one anterolateral spine, and for the branchial and posterolateral margins smooth (vs. rostrum with three spines and three anterolateral spines in M. konara ; vs. lateral margins with six spines in M. nishioi ; vs. lateral margins with several spines in M. ogaensis ; vs. rostrum needle-like and spineless and lateral margins with several spines in M. primaeva ; vs. rostrum needle-like and spineless, three anterolateral spines, and several posterolateral spines in M. quadroblonga ).

Munida grossetana n. sp. represents the youngest record for the genus in the fossil record and the first report of Munida in the Mediterranean area, extending the palaeogeographic distribution for the genus.

Figures

Fig. 1 - Munida grossetana n. sp.A) Holotype, MSNM i28256, dorsal view (×14). B) Idealized reconstruction of dorsal carapace.