Bahadzia caymanensis, Sawicki & Holsinger, 2004

Sawicki, Thomas & Holsinger, John, 2004, Systematics of the subterranean amphipod genus Bahadzia (Hadziidae), with description of a new species, redescription of B. yagerae, and analysis of phylogeny and biogeography, Journal of Natural History 38 (11), pp. 1397-1414 : 1398-1404

Bahadzia caymanensis n. sp.

( figures 1–5 )

Material examined. Cayman Islands. Grand Cayman Island: West Bay Cave , holotype female (5.0 mm), 27 paratypes, J. H. Carpenter, 8 January 1997.

The holotype is deposited in the National Museum of Natural History ( Smithsonian Institution ) under the catalogue number of the former United States National Museum ( USNM 1006978 ); paratypes are in the collection of J. R. Holsinger (H-3667).

Diagnosis. Small to medium-sized stygobitic species that can easily be distinguished from other members of the genus, except Bahadzia yagerae Ortiz and Pérez and B. patilarga Sawicki et al. ( Sawicki et al., 2003) by having a tiny, round, pigmentless eye. The new species differs from B. yagerae by having proportionately longer pereopods 6 and 7, and from B. patilarga by having proportionately shorter pereopods 6 and 7 and shorter antenna 1. Further distinguished from all other species in the genus by possession of two-segemented accessory flagellum on antenna 1. Largest males, 4.5 mm; largest female, 6.5 mm.

Female. Head with tiny round, pigmentless eye or eye spot. Antenna 1 approximately 75% length of body and approximately two times longer than antenna 2; primary flagellum with up to 24 segments, accessory flagellum twosegmented, subequal in length to the first two primary flagellar segments; peduncular segments becoming progressively shorter distally. Antenna 2: flagellum with up to 10 segments; peduncular segment 4 subequal in length to segment 5. Mandible: molar well developed; spine row with about 13 weakly serrate spines; lacinia mobilis of left mandible four-dentate, that of right two-dentate and smaller; incisors of left and right mandibles six-dentate; palp segment 3 approximately 20% shorter than combined lengths of 1 and 2, bearing one long A seta, long row of approximately 9–10 comparatively short D setae and three to four E setae; B and C setae absent. Lower lip: inner lobes poorly developed or vestigial; lateral processes short, rounded apically. Maxilla 1: inner plate with 18 short, lightly plumose setae; outer plate bearing nine pectinate spines; left and right palps similar, expanded and rounded distally, broad apex with eight bladespines and two short, naked setae. Maxilla 2: inner plate narrowing distally, with row of approximately 42 naked submarginal facial setae and row of approximately 14 thicker setae located on extreme inner margin. Maxilliped: apex of inner plate even, armed on inner half with five to six short spines, inner margin with row of 11 weakly plumose setae; outer plate rounded distally, armed with single short spine and numerous setae on distal margin; palp segment 3 pubescent distally, distal inner margin of segment 3 not lobate; palp segment 4 as long as segment 3, nail small and spine-like.

Gnathopod 1: propod subrectangular, about twice as long as broad, posterior margin setose distally, palm short, transverse but lobate at defining angle and bearing four spines on lobe; carpus approximately 40% longer than propod, bearing several clusters of long setae on posterior margin and toward distal end; merus weakly lobiform distally and pubescent; basis with nine long setae on posterior margin; coxa long with about three to four short spines and 11–12 short setae. Gnathopod 2: propod subrectangular about twice longer than propod of gnathopod 1, palm short, oblique, bearing one short spine and two long setae at defining angle, posterior margin with five sets of long setae, anterior margin with five sets of one or two setae; carpus subequal in length to propod, posterior margin with seven clusters of long setae; basis with five long setae on posterior margin; coxa longer than broad, margin with about three to four short spines and seven to eight short setae. Pereopod 3: coxa relatively small, deeper than broad, margin with three short setae. Pereopod 4: coxa broadly expanded distally and excavate posteriorly, margin with 15 short setae. Pereopod 6 approximately 80% length of body, approximately 25% longer than pereopod 7 and approximately 35% longer than pereopod 5. Pereopods 5–7: basis relatively narrow, with rather large, bluntly rounded distoposterior lobes. Dactyl of pereopod 5 approximately 30% length of corresponding propod; dactyls of pereopods 6 and 7 approximately 33% and 26% length of corresponding propods, respectively. Coxal gills on pereopods 2–6 subovate, with short peduncle, very large on pereopods 2–4. Brood plates sublinear, small relative to gills.

Pleonal plates: posterior margins with one setule each, posterior corners small but distinct, ventral margin of plate 1 without spines, plate 2 with one spine, plate 3 with two spines. Pleopods normal, two rather long coupling spines on peduncle. Uropod 1: inner ramus shorter than peduncle, longer than outer ramus, bearing about six spines; peduncle with 11 spines, one of which is basofacial in position. Uropod 2: inner ramus subequal to peduncle, longer and broader than outer ramus, armed with 10 spines; outer ramus with about six spines; peduncle with nine spines, six forming a comb row on dorsodistal end. Uropod 3 approximately 13% length of body; inner ramus subequal in length to outer ramus, margins with short spines and plumose setae; outer ramus with short terminal segment, inner margin with plumose setae and a few spines, outer margin with spines only; peduncle with five spines. Telson rather long and narrow, in two separate lobes; lateral margins with about two to five small spines, none in sets of two; medial margins with two to three small spines, apices each with one or two short spines and three long, distally plumose setae.

Male. Differing from female in structure of gnathopod 2 as follows: dactyl and propod proportionately longer; propod palm long, oblique, with double row of about six blunt-tipped spines, defining angle with two long and one short setae, posterior margin longer than palm, with four sets of setae.

Etymology. This species is named for its occurrence on Grand Cayman Island.

Distributional ecology. This species is known only from its type-locality, West Bay Cave. According to J. H. Carpenter (personal communication) the typespecimens were collected from a shallow, weakly brackish pool in a small cave. Very little is known about the ecology of the type-locality for B. caymanensis , and it is unclear if the specimens were restricted to the weakly brackish shallow water pool or washed out from a lower anchialine cave habitat.

Figures

FIG. 1. Bahadzia caymenensis, sp. nov. Holotype female, 5.0 mm: (A) entire animal from right side. Paratype female, 6.5 mm: (B) antenna 1; (C) uropod 3; (D) uropod 2 (distomedial comb-spine row enlarged); (E) uropod 1.

FIG. 2. Bahadzia caymenensis, sp. nov. Paratype female, 6.5 mm: (A) antenna 2; (D) maxilla 1; (E) palp of other maxilla 1; (F) maxilliped; (G) maxilla 2; (H) lower lip. Paratype female 5.7 mm: (B) right mandible; (C) incisor and lacinia mobilis of left mandible.

FIG. 3. Bahadzia caymenensis, sp. nov. Paratype female, 6.5 mm: (A) pereopod 7; (B) pereopod 4; (C) pereopod 3.

FIG. 4. Bahadzia caymenensis, sp. nov. Paratype female, 6.5 mm: (A) pereopod 6; (B) gnathopod 2; (C) enlarged distal end of propod and dactyl of gnathopod 2.

FIG. 5. Bahadzia caymenensis, sp. nov. Paratype female, 6.5 mm: (A) pereopod 5; (C) telson; (D) pleopod 1 (coupling spines enlarged); (E) gnathopod 1; (F) enlarged distal end of propod and dactyl of gnathopod 1. Paratype male 4.5 mm: (B) propod and dactyl of gnathopod 2.