Munidopsis geyeri Pequegnat & Pequegnat, 1970

Macpherson, Enrique & Segonzac, Michel, 2005, Species of the genus Munidopsis (Crustacea, Decapoda, Galatheidae) from the deep Atlantic Ocean, including cold-seep and hydrothermal vent areas, Zootaxa 1095 (1), pp. 1-60 : 25-27

Munidopsis geyeri Pequegnat & Pequegnat, 1970 ( Fig. 6 )

Munidopsis geyeri Pequegnat & Pequegnat, 1970: 149 , figs 5–9, 5–10; 1971: 19.— Baba, 2005: 163, fig. 76.

Material examined. Azores Islands , BIACORES, Stn 202, 37º26.5'N, 25º00'W, 2900 m, 06.11.1971: 1 female 13.0 mm. Florida Escarpement, ALVIN 3637 , 26º01.8’N, 84º54.9’W, 3288 m, 30.10.2000: 1 male 17.6 mm, 2 females 8.1–10.2 mm. Off Angola, BIOZAIRE 1, Stn PL 81­5 , 05°47.80’S, 09°42.60’E, 3151 m, 10.01.2001: 1 male 32.2 mm. Off Angola, BIOZAIRE 2, Stn PL 147­10 , 05°47.80’S, 09°42.60’E, 3151 m, 01.12.2001: 5 males 25.7–42.0 mm, 2 females 27.5–28.2 mm. Off Angola, BIOZ­RECUP, Stn MAC 10, 05º51’S, 09º41.98’E, 3155 m, 31.01.2003: 5 juv. 3.3–4.2 mm. Off Angola, BIOZAIRE 3, Stn CP 16, 05°49.79'S, 09°44.08'E, 3172 m, 28.12.2003: 1 female 6.8 mm.— Stn CP 19, 05°48.07'S, 09°41.60'E, 3184 m, 31.12.2003: 1 male 35 mm.— Stn CP 20, 05°46.89'S, 09°44.66'E, 3113 m, 02.01.2004: 39 males 8.9–40.5 mm, 14 ovig. females 31.5–46.9 mm, 39 females 19.9–46.9 mm .

Remarks. The species was synonymized with M. subsquamosa Henderson, 1885 by Ambler (1980). However, more recent studies have demonstrated the validity of M. geyeri as a separate species ( Gore 1983; see Baba 2005, for a complete discussion of the taxonomic status of the species).

Munidopsis geyeri belongs to the group of species having the carapace with 2 epigastric spines only, the anterolateral spine small, subequal to the antennal spine in size, directed straight forward, the rostrum spiniform, the abdominal segment 6 with the posteromedian margin weakly convex, not produced, the eyestalks short relative to length, the mesial eye­spine present, the first walking leg overreaching the end of the chelipeds, the fixed finger of the chelipeds without denticulate carina on the distolateral margin, the dactyli of the walking legs strongly curved distally, the ultimate flexor marginal tooth much closer to the penultimate than to the tip of the article, and epipods on the chelipeds.

Size distribution. The specimens collected on the west African equatorial margin, north of the Zaïre River channel, were mostly caught in the trawl CP 20 during the BIOZAIRE 3 Cruise carried out on the Regab cold­seep area. The sex ratio of these specimens was not significantly different from 1:1 (chi­square, p>0.05). However, males were more abundant in the smaller size classes than females ( Fig. 6 ). The ovigerous females were first measured at 31.5 mm.

Distribution and habitat. Munidopsis geyeri was described from specimens collected in the southwest Gulf of Mexico, Colombia and Venezuela Basins and south of Jamaica, between 2650 and 4151 m, ( Pequegnat & Pequegnat 1970, 1971, Gore 1983, Baba 2005). The specimens from the Caribbean Sea were caught on bottoms of yellow clay mud, with vegetable debris, and with abundant sponges and holothurians ( Gore 1983). The present record extends the geographical range of the species to the South (Gulf of Guinea) and Central Atlantic (Azores Islands). The depth range is 2650 to 4151 m.

The species also occurs the Florida Escarpment (Gulf of Mexico, 3288 m; Turnipseed et al. 2004) and at the Regab site (Gulf of Guinea, 3150 m, Fig. 14 ; Andersen et al. 2004, Komai & Segonzac 2005, Ondréas et al. 2005), among an abundant chemosynthetic community associated with cold­seeps. These two communities are similar, characterized by the presence of sea anemones, dense populations of vestimentiferan tubeworms, large mytilid bivalves, gastropods, alvinocaridid shrimps, chiridotid holothurians and zoarcid fish.

The stomach contents of five specimens collected in the Regab site (BIOZAIRE 3, CP20) showed very small quantities of fine gray sediments. The SEM observations also showed agglomerations of some mineral particles, diatoms, and decapod crustacean remnants, a few small sea­urchin spicules, and five micro­gastropod shells. One microgastropod shell contained flesh probably belonging to Hyalogyrina sp. (Vetigastropoda, Skeneiformes), an inhabitant of reduced environments, and known to graze bacterial film (A. Warén, personal communication).

Figures

FIGURE 6. Size­frequency distribution (carapace length, mm) of males (M), ovigerous females (F ov) and females (F) of Munidopsis geyeri from the trawl CP20, Cruise BIOZAIRE 3 (Gulf of Guinea), n= 92.

FIGURE 14. Munidopsis geyeri Pequegnat & Pequegnat, 1970, in situ observations. A, two specimens among cold­seep community at the base of Florida Escarpment (Gulf of Mexico, 3266 m) with tubeworms vestimentiferan Escarpia laminata (Jones, 1985); substratum: carbon crust. Photo taken by the submarine Alvin in Oct. 2000 (I. MacDonald, USA). B, two specimens on reduced sediment and outcrops of white gas hydrates; with a dead turrid gastropod Phymorhynhus sp.? Photo taken at the Regab cold­seep site (Gulf of Guinea, 3150 m) by the ROV Victor in Jan. 2001 (Ifremer/Biozaïre 2).