Bosmina (Lunobosmina),

Kotov, Alexey A., Ishida, Seiji & Taylor, Derek J., 2009, Revision of the genus Bosmina Baird, 1845 (Cladocera: Bosminidae), based on evidence from male morphological characters and molecular phylogenies, Zoological Journal of the Linnean Society 156 (1), pp. 1-51 : 23-29

SUBGENUS BOSMINA (LUNOBOSMINA) TAYLOR ET AL., 2002

Eubosmina (Lunobosmina) Taylor et al., 2002: 1494 .

Type species: Bosmina (Eubosmina) oriens De Melo & Hebert, 1994 , typified by monotypy, case 68.3 of ICZN (2000).

Subgenus diagnosis based on male characters: Distal portion of postabdomen as in female, not inflated, preanal margin slightly depressed, with relatively long, fine setules. Gonopore opens subdistally. Postabdominal claw long, without a terminal spinule. Basal pecten of denticles not shifted from postabdominal claw to body of postabdomen, consisting of thin spines, distal pecten consisting of short, fine setules. Antenna I with widened pre-aesthetasc portion. A seta located at a distance from two others on the subdistal lobe of limb I. Seta 6 on limb I short.

Comment: The sole species of the subgenus, B. oriens , has a lateral head pore of the ‘ Eubosmina ’ type. But, B. oriens is the most primitive member of the ‘ Eubosmina –Liederobosmina ’ clade because it has a non-specialized postabdomen (an uninflated and a non-conical distal end with a gonopore located far from the distal end). Because of these traits, the postabdomen of B. oriens is more primitive than those of Eubosmina , Liederobosmina, or Sinobosmina . Also, B. oriens has a primitive, thick tip of the copulatory hook, in contrast to the elaborated tip of Liederobosmina. So, although B. oriens might be the distant sister lineage to Liederobosmina, the subgenus Lunobosmina retains several plesiomorphic characters.

Bosmina (Lunobosmina) oriens ( De Melo & Hebert, 1994)

Figures 13–16

Eubosmina longispina (Leydig, 1860) in Deevey & Deevey, 1971: 206–209; pl. 1: fig. 3a, b; pl. 3, fig. 3a–d (part).

Bosmina (Eubosmina) oriens De Melo & Hebert, 1994: 1815–1818 , fig. 6G, H.

Eubosmina (Lunobosmina) oriens De Melo & Hebert in Taylor et al., 2002: 1494.

Type locality: ‘A lake located on the north side of highwayhighway 44, 3 km east of the Rhode Island – Connecticut state line 41°55′N; 71°45′W)’ ( De Melo & Hebert, 1994), Rhode Island, USA. This body of water is locally named Bowdish Reservoir .

Type material: Holotype. A parthenogenetic female, CMN . Paratypes. ten adult and six juvenile females, CMN .

Material

Populations containing males: USA. Hell Hollow Pond , Connecticut, AAK 2004-051 (the former artificially induced by adding MF to the culture, see Kim et al., 2006) .

Canada. Pond on highway 1, 2.9 km east of Little Harbor junction, Newfoundland, collected on 4 September 1984 by D. G. Frey, DGF 7092; Barren Pool, 1.4 km west of Rocky River bridge, west of Colinet, Newfoundland, collected on 9 September 1984 by D. G. Frey, DGF 7121; Fen Pool, east side of road from Cape St. Mary’s to highway 100, Newfoundland, collected on 11 September 1984 by D. G. Frey, DGF 7135a; a body of water near highway 1, Newfoundland, collected in September 1984 by D. G. Frey, DGF 7167-II; bog pool 12, Barrents near Daggett’s Round Pond near Bavline, north of St. John’s, Newfoundland, collected on 24 September 1984 by D. G. Frey, DGF 7186; Pine Hill Pond, Terra Nova National Park, Newfoundland, collected on 30 September 1984 by D. G. Frey, DGF 7202; Peskowesk Lake, east of where canoes are put in, Kefimkujik National Park, Nova Scotia, collected on 13 October 1984 by D. G. Frey, DGF 7280.

Parthenogenetic populations: USA. Bowdish Resevoir (type locality), Rhode Island, collected in June 2004 by D. J. Taylor & A. A. Kotov, AAK 2005-236 - 237 ; Hell Hollow Pond , Connecticut, collected in June 2004 by D. J. Taylor & A. A. Kotov, AAK 2005-238 - 239 ; Fresh Pond, Dennis , Massachusetts, collected in June 2004 by W. Piel & A. A. Kotov, AAK 2005-258 ; Great Pond, Cape Cod , Massachusetts, collected in June 2004 by W. Piel & A. A. Kotov, AAK 2005-251 ; Pond 3, Three ponds, Long Island , New York, collected in June 2006 by D. J. Taylor & A. A. Kotov, AAK 2005-209 .

Canada. Roadside Lake, highway 333, 0.8 km east of East Dover , Nova Scotia, collected on 21 October 1984 by D. G. Frey, DGF 7300 .

Redescription

Adult parthenogenetic female ( Fig. 13 ): Body wide in anterior view, short and wide in lateral view, dorsal margin in general regularly curved from distalmost extremity to posterodorsal angle, posterior margin straight, its height about half of the body height, ventral margin almost straight, with a depression anterior to mucro. Reticulation very obscure, both on head and on valves. Head with well-developed ocular dome, and consequently with a distinct preocular depression that is obvious in lateral view, rostrum blunt, regularly arched. Frontal head pore small, located closely to ventral margin of head (as seen from anterior side), and significantly ventral to level of antennular sensory setae. Median head pore minute, located posteriorly to ocular dome. Fornices well-developed, covering coxal part of antenna II. Lateral head pore small, with a raised ring-like margin, located at a great distance from ventral margin of head shield, above level of mandibular articulation. Compound eye very large. Labrum as a fleshy appendage lacking significant projections, distal labral plate small. Ventral valve margin with a series of stout setae, the bases of which are located on its internal surface, the more anterior setae supplied with long setules. Seta kurzi with small setules, located on internal side of valve anterior to the aforementioned depression near the mucro, which is strong and long even in large adults, with a truncated tip and one or two incisions on the ventral side, sometimes the incisions are completely absent. On inner side of mucro, there are few relatively strong denticles, as a continuation of a series of setules at the posterior valve margin.

Thorax relatively long, with six limb pairs, abdomen short, with transverse rows of setules. Postabdomen strongly compressed laterally, with width approximately equal along entire length, and with ventral (functionally dorsal!) margin slightly convex. Preanal margin long, slightly concave, with few groups of setules distally. Sides of postabdomen supplied with series of finer setules. Distal (anal) margin nearly directly truncated, posterodorsal angle as a small projection. Postanal portion as a cylindrical projection bearing paired postabdominal claws. Each claw regularly bent, with three denticles on convex (ventral) margin and two pectens on concave (dorsal) margin: distal pecten consists of fine setules, whereas proximal pecten consists of between seven and nine rather strong, sparsely located teeth. Near the claw on the postanal portion of the postabdomen there is a third, pre-claw pecten of minute denticles. Postabdominal seta shorter than preanal margin, with its distal segment about two times shorter than distal one, supplied with fine, long setules.

Antenna I fused with rostrum, rather short, its length from tip to tip of rostrum about 0.3–0.4 body lengths. Antennular (frontal) sensory seta located on rostrum in region of preocular depression. Free (not incorporated in rostrum) part of antenna I consists of a pre-aesthetasc portion, fused with rostrum, and post-aesthetasc portion, the presence of which is a unique synapomorphy of Bosmina . Pre-aesthetasc portion straight, regularly narrowing in anterior view, with an internal spine near a flat site of the aesthetasc bases. Nine aesthetascs that are delicate, slightly differing in size, with the longest somewhat shorter than the pre-aesthetasc free portion. Postaesthetasc portion directed ventrally and somewhat posteriorly, slightly curved in lateral and anterior views. Both portions supplied with crossing series of fine denticles.

Antenna II typical for the genus, with six pairs of thoracic limbs, and with morphology indistinguishable from that in other species ( Kotov, 1996).

Juvenile female ( Fig. 14A–F ): Body more compressed laterally and more elongated in lateral view, with obvious reticulation. Ocular dome less developed, especially in instar I; median head pore as in adult, posterior dorsal head pore presents in instar I. Lateral head pore closer to mandibular articulation. Mucro long, with several denticles at ventral margin. Antenna I longer (especially its post-aethetasc portion), strongly curved in lateral and anterior view, head pore at level of antennular sensory setae.

Ephippial female: In lateral view habitus similar to adult parthemogenetic female, a longitudinal fold on dorsal part of valves of large ephippial females, a median fold on top of dorsum, so dorsum is triangular in cross section.

Adult male ( Figs 15 and 16 ): Body relatively high, dorsum posteriorly slightly concave, posterior margin of valves of moderate height. Head large, anteroventral angle projected; distalmost extremity of head with slight ocular dome or without it. Lateral head pore at a long distance from lateral edge of head shield. Mucro long, seta kurzi long, a series of long setae at anteroventral portion of valve. Postabdomen massive, ventral margin straight, preanal margin slightly concave, dorsodistal angle slightly projected, anal margin straight, in a small anal depression. Postanal portion of postabdomen short, conical, blunt distally, supplied with series of fine spinules, spinules in a pre-claw group somewhat larger than rest. Single gonopore opens on dorsal side, far from distal end. Postabdominal claw long, slender, without distal spinule, distal pecten as a series of fine setules, proximal pecten with slender denticles. Antenna I with base not inflated, regularly narrowing distally, characteristically E-shaped. Sensory seta long, male seta long, located on a minute pedestal. Antenna II with two short sensory setae on coxal part. Distal sensory seta long, reaching distal end of basal segment of endopod. Limb I with idl strongly inflated, with a low hillock on the basal portion, and with its distal portion relatively short, terminating as a long, naked seta. Copulatory hook relatively large and thick, not recurved to a parallel position with the idl, tip of hook blunt, with fine setules. Subdistal lobe massive, with a long seta, a rudimentary seta near it, and another rudimentary seta at a distance from the two aforementioned setae.

Juvenile male I: Not studied.

Juvenile male II ( Fig. 14G–M ): Body shape as in juvenile female II, with a slight ocular dome. Postabdomen with slightly depressed preanal margin, postanal portion slightly inflated, rudimentary gonoduct that does not reach the level of anus. Postabdominal claw long, distal pecten with fine setules, proximal pecten with slender teeth, pre-claw pecten with fine setules. Antenna I fused with rostrum, with a sensory seta and a short male seta approximately at the same level. Antenna II with two short sensory setae on coxal portion, and a rudiment of distal sensory seta. Limb I with idl large (but smaller than in adult), its distal portion subovoid, with a seta approximately as long as distal portion, and with a second rudimentary seta; copulatory hook robust, with blunt tip, subdistal lobe small, with two setae of equal lengths, and a massive hillock (a rudiment of the third seta).

Size: Females, 380–630-Mm long; adult males 465– 510-Mm long.

Distribution: This is a species with a relatively local distribution on the Atlantic Coast of the USA and Canada.

Comments: The species was briefly described by Deevey & Deevey (1971) as Eubosmina longispina : they illustrated the adult males bearing characteristic E-shaped antenna I ( Fig. 15C, D ). Later, Kotov (1996) noted that the male described by Deevey & Deevey had a postabdomen of the Neobosmina - type (now Liederobosmina) – very different from the beveled postabdomen of the males from European Bosmina (Eubosmina) longispina . De Melo & Hebert (1994) created a new species based largely on allozyme evidence, without examination of the males. The DNA sequence-based phylogeny of Taylor et al. (2002) indicated a distant relationship of B. oriens with B. longispina , and they created a new subgenus Eubosmina (Lunobosmina) containing B. oriens . However, Taylor et al. (2002) also proposed that the ‘ B. longispina ’ of Deevey & Deevey (1971) was actually B. oriens . Later, Kim et al. (2006) induced males of B. oriens and confirmed that the unusual male antenna I indeed unites B. oriens with B. longispina sensu Deevey & Deevey (1971) . Our more detailed analysis of male morphology further supports the opinion that B. oriens is the species that Deevey& Deevey termed North American B. longispina . We note that endemic B. longispina -like species do exist in North America in addition to B. oriens .

The morphology of parthenogenetic females of the common North American species of subgenera Eubosmina and Liederobosmina have not been well studied. Previous authors concentrated on such characters as the length of the mucro or of antenna-I ( Lieder, 1991), instead of attempting to find other characters that are less vulnerable to the influence of ecological factors. Females of B. oriens are difficult to discern from females of North American Bosmina (Eubosmina) sp. Bosmina oriens does seem to possess a relatively large mucro and relatively strong denticles on its inner side that are absent in the Eubosmina . In contrast, males are easily diagnosed after scoring the characteristic E-shaped antenna I and a unique, primitive postabdomen.

Figures

Figure 13. Bosmina (Lunobosmina) oriens: adult female from a pond on highway 1, 2.9 km east of Little Harbor junction, Newfoundland, Canada. A, B, lateral view; C, head, lateral view; D, E, head, anterior view; F, region of lateral head pore; G, setae at anteroventral portion of valve, inner view; H, I, mucro, inner view; J, K, postabdomen, lateral view; L, postabdominal claw. Scale bars: 100 Mm.

Figure 14. Bosmina (Lunobosmina) oriens: juvenile female from a pond on highway 1, Newfoundland, Canada (A, C–F), and from Great Pond, Cape Cod, Massachusetts, USA (B); juvenile male II from Hell Hollow Pond, Connecticut, USA (G–M). A, B, general view of juvenile female; C, anterior view of juvenile female; D, antennular sensory setae and frontal head pore of juvenile female; E, lateral head pore of juvenile female; F, mucro of juvenile female; G, juvenile male II, general view; H, head of juvenile male II, anterior view; I, mucro of juvenile male II, inner view; J, postabdomen of juvenile male II; K, setae at coxal part of antenna II of juvenile male II; L, rudimentary sensory seta at distal segment of antenna II of juvenile male II; M, distal portion of limb I of juvenile male II. Scale bars: 100 Mm.

Figure 15. Bosmina (Lunobosmina) oriens: adult male from a pond on highway 1, Newfoundland, Canada (A, B, D–F, H, I), and from Hell Hollow Pond, Connecticut, USA (C, G, J). A, B, lateral view; C–E, head, lateral view; F, G, head, anterior view; H–J, mucro, inner view. Scale bars: 100 Mm.

Figure 16. Bosmina (Lunobosmina) oriens: adult male from a pond on highway 1, Newfoundland, Canada (B–E, G, I–M), and from Hell Hollow Pond, Connecticut, USA (A, F, H, J). A, setae at anteroventral portion of valve, inner view; B–D, postabdomen; E, antenna I, anterior view; F, G, region of aesthetasc location, anterior view; H, region of aesthetasc location, inner view; I, antenna II, anterior view; J, sensory setae at coxal part of antenna II. Scale bars: 100 Mm.