Spgologia 2 (112) 1986, E. J. Brill, Leiden BERMUDAMYSIS G. N., PLATYOPS G. N. AND OTHER MYSIDS FROM BERMUDIAN CAVES MIHAI BACESCU Muste dYHistoireNaturelle "Grigore Antipa", 1 ChaussCe Kisselef, ~ucuresti111, Romania THOMAS M. ILIFFE Bermuda Biological Station for Research, Ferry Reach 1- 15, Bermuda SUMMARY One of the authors (T. Iliffe) collected mysids from 9 caves, within the framework of a faunistic survey of Bermudian caves. A brief characterization of the caves and the collecting technique is presented. Two new genera, each with a new species - i.e. Bewnudamysis speluncola n.g., n.sp. and Platyops stnrm' n.g., n.sp. - are described. The first species was collected in dozens of specimens from numerous caves; the second shows dorsoventrally flattened eyes, a convergency with the genus Heteromysoides, although the new genus seems to belong to the Mysini tribe. Morphological and zoogeographical remarks are made on another mysid common in those caves, Heteromysis bmnudmsis Sars, 1885, as well as on a fourth species, H. guitarti Bacescu, 1978. L'un des auteurs (T. Iliffe) a collectt des MysidacCs dans 9 grottes dans le cadre d'une etude faunistique des grottes des Bermudes. On donne une brkve description des grottes en question et de la technique de capture des MysidacCs. On fournit des descriptions de deux genres nouveaux, chacun avec une nouvelle espkce, i savoir Bmnudamysis speluncola n.g., n.sp. et Platyops stmeri n.g., n.sp. La premikre espsce a CtC capturCe en des dizaines d'exemplaires dans un grand nombre de grottes; la seconde a des yeux aplatis dorsoventralement, convergence avec le genre Heteromysoi&s, bien que Platyops semble ap- partenir B la tribu des Mysini. On fait des remarques morphologiques et zooghographiques concernant deux autres MysidacCs, Heteromysis bewnudmsis Sars, 1885 et H. guitarti Bacescu, 1978. INTRODUCTION The extensive inland marine caves of Bermuda constitute a diverse habitat containing over 200 species of macro-invertebrates (Sket 81 Iliffe, 1980; Iliffe et al., 1983). The caves are situated in the Pleistocene eolian limestones which cap a mid ocean volcanic sea mount. The most unusual and specialized animals have been found in those tidal cave pools and underwater chambers 94 BERMUDA MARINE CAVE SYMPOSIUM most isolated from the sea. Utilizing advanced cave diving techniques, many of the animals have been collected from the deeper waters of the pools and often at considerable penetrations into the underwater caves - areas previously unknown or thought to be inaccessible. The three areas of zonation applicable to terrestrial caves - a twilight zone near the entrance, a middle zone of complete darkness and variable temperature, and the deep interior zone of darkness and constant temperature (Poulson & White, 1969) - are found in these marine caves. While the diversi- ty and abundance of organisms decrease with distance inland, away from the sea, it is in these far reaches of the caves that the most significant troglobitic species have been discovered. New species described from the Bermuda caves include Atlantusellus caver- nicolus, an isopod representing a new family (Sket, 1979); Miostephos leaming- tonensis, a new calanoid copepod (Yeatman, 1980); Apseudes bermudeus, a new hermaphroditic tanaidacean (Bacescu, 1980); Cocoharpinia ilzffei, a gammari- dean amphipod from a new genus (Karaman, 1980a); Idunella sketi, a new species of gammaridean amphipod (Kararnan, 1980b); Somersiella sterr& and Typhlatya iltffei, two new species of caridean shrimp (Hart & Manning, 1981); Mesonerilla prospers, a new archiannelid polychaete (Sterrer & Iliffe, 1982); and Bermudalana aruboides, representing a new genus of cirolanid isopods (Bowman & Iliffe, 1983), and Mictocaris halope described by Bowman & Iliffe (1985), a representative of a new order (Mictacea) of Peracarida. COLLECTION SITES In order to avoid repetition when indicating the materials and describing the species, we shall henceforth use only the numbers designating each of the 9 sta- tions. St. 1: Green Bay Cave, 13 June 1982, specimens taken from a white sponge collected using scuba in the Connection Passage near the Rat Trap at 16 m water depth. St. 2: Green Bay Cave, 31 January 1984, specimens collected using scuba with a fine mesh hand net from bottom silt in the "Desert" in 15 m water depth. St. 3: Castle Grotto, 20 July 1982, specimens collected with a suction bottle from bottom silt of the rear portion of the main pool in 0.5 to 1 m water depths. St. 4: Cheny Pit Cave, 12 January 1984, specimens collected using scuba with a suction bottle from the sloping silt floor in 8 to 12 m water depths. St. 5: Palm Cave, 13 & 16 March 1982, specimens collected using scuba with a suction bottle and fine mesh hand net from bottom silt in the underwater Palm Cave Room at 16 m water depth. St. 6: Walsingharn Cave, 17 February 1984, specimens collected with a fine mesh hand net from bottom rocks in the main entrance pool at 2 to 3 m water depths. St. 7: Leamington Cave, 14 August 1984, specimens taken in a plastic bottle trap baited with squid and left for 4 days at 5 m water depth in the main pool. St. 8: Green Bay Cave, 15 August 1984, specimens collected using scuba with a suction bottle and fine mesh hand net from bottom silt in the "Desert" at 15 m water depth. St. 9: Grenadier Pool, 15 August 1984, specimens collected using scuba with fine a mesh hand net and bottles from under a rock ledge in 5 m water depth. STYGOLOGZA 2 (112) 1986 95 HABITAT Green Bay Cave is Bermuda's longest cave at over 2 km in length, despite be- ing almost totally underwater. It consists of 2 principal passages, the Green Bay Passage and the North Shore Passage, which extend across a peninsula of land separating the nearly enclosed Harrington Sound from the open North Lagoon. Linking these 2 segments of the cave are the Trunk Passage and its extension, the Connection Passage. The Rat Trap is a low area with stronger currents just inside the Green Bay entrance where the Green Bay and Connec- tion Passages branch. The "Desert" is a segment of the Connection Passage with a broad silty floor. Castle Grotto is a former commercial cave with a large shallow lake and was shown to tourists by boat during the 1930's. It is located on the edge of Castle Harbour and has direct tidal connections with it. Cherry Pit Cave is in the Walsingham area and consists of a steeply sloping fissure extending from the surface to an underwater room. Palm Cave is part of a large, multi-entrance underwater cave system extend- ing inland from Harrington Sound towards Castle Harbour. Walsingham Cave is similarly part of another extensive cave system located near Castle Harbour. A lake in the dimly illuminated entrance section of the cave has tidal currents passing through it. Leamington Cave is presently shown to tourists. An artificially illuminated lake within the cave connects to Harrington Sound. Grenadier Pool is a nearly circular water-filled collapse sink located about 75 m from the North Shore of Bermuda. Underwater, the sink extends horizontal- ly beneath a rock ledge for about 10 m to a dimly illuminated section. DESCRIPTIONS In the material from these caves, we found four species of Mysidacea: one described from Bermuda by G. 0. Sars in 1885 (i.e. Heteromysis bemudensis) whose male we now describe and whose diagnose we complete; one known from Cuba (i.e. Heteromysisguitartt); and two representing new genera as well as new species. Bermudamysis new genus Diagnosis. - Small translucent red mysids (2.8 - 4.0 mm) of the Mysini tribe, distinguished within the tribe through the lack of pleopodal dimorphism; long and fine appendages; very elongate pereiopods IV-V (0,Q) with thin articles and $.-segmented tarsus, the first pereiopods shorter and a bit thicker, with 3-segmented tarsus. Globular eyes: the corneal part smaller than the cylindrical peduncle. 96 BERMUDA MARINE CAVE SYMPOSIUM Two marsupial laminae with 2 or 4 eggs; lanceolated, antenna with feathered setae all around. Telson armed with 5-6 spines only in its distal half, with a deep sinus bordered by long apical spines and 6-7 lamina. Uropodal endopodite without spines. Bermudamysis speluncola new species. (fig. 1 A. - J.) Material - Dozens of 0 and Q specimens from the following stations: St. 1 (2 Q , 3 W, 1juv.); St. 2 (40 Q , 50 W, 5 juv.); St. 3 (1 Q); ST. 4 (4 Q ov., 1 Q P, 3 a); ST. 5 (14 Q , 12 0,1 Q p.); St. 6 (27 specimens among which 5 were ovigerous 9); St. 7 (1 Q , 2 a j.); St. 8 (3 expl.); St. 9 (117 a & Q : a few juv.). Description of the male and the female - Size: 2.3 - 3.0 mm. Integument slightly transparent, having a red tint; several specimens fixed some time ago show only the brown-golden visual part of the eyes. But during the life span the mysid has a bright and beautiful colour in spite of keeping its transparency, a colour dominated by intense red; this colour covers the whole cephalothorax (excepting the golden eggs), the basis of the thoracic appendices, joints of the abdominal segments and especially the last joint binding the pleotelson to the last abdominal segment. Reddish-orange starlets are also present on the scales, antennae, base of the long flagellum Al , telson and uropods. Yellowish-orange occular peduncles, corneal part externally translucent with a bright brown nucleus. After preservation in alcohol for as little as 4 months, this crustacean becomes milky-white in colour and half-transparent all over; cephalothorax dull-white; only occular peduncles keep their yellow col- our, while the visual part shines due to its brownish-red colour.