Attheyella (Neomrazekiella) tessiae, Bang, Hyun Woo, Baguley, Jeffrey G. & Moon, Heejin, 2015

Bang, Hyun Woo, Baguley, Jeffrey G. & Moon, Heejin, 2015, First record of harpacticoid copepods from Lake Tahoe, United States: two new species of Attheyella (Harpacticoida, Canthocamptidae), ZooKeys 479, pp. 1-24 : 4-7

Taxon classification Animalia Harpacticoida Canthocamptidae

Attheyella (Neomrazekiella) tessiae sp. n. Figs 7, 8, 9, 10

Type locality.

The Lakeside littoral zone; 38°57'42"N, 119°57'14"W, 5 m water depth, of Lake Tahoe in California-Nevada, United States.

Material examined.

Holotype: 1♀ (USNM No: 1251796) dissected on 9 slides, from the type locality. Paratype 1♀ and 1♂ (USNM No’s listed in order presented in text: 1251797, 1251798) each dissected on 3 and 9 slides respectively, and 10♀♀ and 6♂♂ (USNM No’s for specimens in vials (female, male): 1251799, 1251800) in 70% ethanol, vial. Additional samples were deposited in the first author’s collection. All from the type locality, July 2013, leg. J. G. Baguley.

Description.

Female. Total body length 660 µm (n=5; range: 635-694 µm), measured from anterior margin of rostrum to posterior margin of caudal rami. Largest width measured at posterior margin of cephalic shield: 176 µm. Urosome narrower than prosome (Fig. 7A).

Cephalothorax (Fig. 7A) bell-shaped, with oval dorsal integumental window and some scattering sensillae on dorsal surface and along lateral margin. Rostrum (Fig. 7B) small and triangular, completely fused to cephalothorax and with pair of sensilla and pore near anterior margin.

Prosome with smooth posterior margins, pleural areas well developed. Body slightly constricted between each somite. All pedigerous somites with plain hyaline frill on posterior margin. Urosome 5-segmented, comprising P5-bearing somite, genital double-somite and 3 free abdominal somites.

Genital double-somite as wide as long. Original segmentation marked by discontinuous internal chitinous rib laterally, completely fused ventrally. A row of spinules present on lateral side of genital field. Genital field located far anteriorly (Fig. 7C). Genital apertures paired, closely set together. Copulatory pore located anteriorly between genital apertures. Seminal receptacle well developed on each side. P6 with small protuberance bearing 2 bare unequal setae.

Anal somite (Fig. 7 D–E) with well-developed rounded operculum. Surface ornamentation consisting of a pair of sensilla dorsally and a pair of pores ventrally, posterior margin with spinules ventrally and dorsally, with triangular process dorsally, anal opening with a fringe of fine setules. Caudal rami short, as long as wide, each ramus with 7 setae: setae I-II small, closely set, seta III bare, seta IV pinnate, seta V bipinnate and longest, seta VI bare, seta VII tri-articulate at base.

Antennule (Fig. 7B) 8-segmented. Segment 1 largest, with 1 spinular row around posterior margin and 1 pinnate seta. Segment 4 with aesthetasc fused basally to seta and arising from a pedestal. Armature formula: 1-[1], 2-[8], 3-[5], 4-[1+(1+ae)], 5-[1], 6-[3], 7-[2], 8-[4+acrothek]. Apical acrothek consisting of a small aesthetasc fused basally to 2 bare setae.

Antenna, mandible, maxillule, maxilla, and maxilliped as in Attheyella (Attheyella) tahoensis sp. n.

P1 (Fig. 8A) with well-developed coxa with spinular row on anterior surface. Basis with setules along outer margin and anterior surface, with pinnate outer and inner spines. Endopod 3-segmented, 1.3 times as long as exopod; enp-1 longer than enp-2, with one inner pinnate seta; enp-2 with 1 bipinnate inner seta; enp-3 with a small inner seta, and 1 long geniculate seta and 1 pinnate seta distally. Exopod 3-segmented, reaching end of enp-2, exopodal segments with strong spinules along outer margin and outer distal corner; exp-3 with 2 geniculate distal setae and 2 strong spinulose outer spines.

P2 (Fig. 8B) with small triangular praecoxa, with row of spinules on anterior surface along distal margin. Coxa nearly 1.5 times as wide as long, ornamented with row of long spinules along outer margin; Basis with outer pinnate spine; P2 enp-2 more than twice as long as enp-1; with 1 short, pinnate inner seta; enp-2 with 1 inner pinnate seta, and 2 distal bipinnate setae and 1 bipinnate outer seta; exopod 3-segmented; each segment with row of spinules along outer margins; third segment about 2.3 times as long as second segment with 3 bipinnate outer spines, 1 apical pinnate spines and 1 plumose seta, and 1 inner long bipinnate seta.

P3 (Fig. 8C) with small praecoxa. Coxa nearly 1.5 times as wide as long, with row of spinules along outer margin. Basis with outer pinnate seta and spinular row along outer margin. Endopod-1 with 1 bare inner seta; enp-2 with 2 inner naked setae, and 1 pinnate seta and short distal spine; exp-3 about twice as long as second segment with 3 bipinnate outer spines, 2 apical pinnate spines and 2 long bipinnate inner setae.

P4 (Fig. 8D) with small and triangular praecoxa. Coxa with spinular row along outer margin. Enp-2 with 2 inner pinnate setae, and 3 pinnate setae, the innermost longest; exp-3 with 3 bipinnate outer spines, 2 apical pinnate setae and 2 long bipinnate inner setae. Spine and setal formulae as follows:

P 5 (Fig. 8E). Baseoendopod forming short, outer setophore bearing the basal seta. Endopodal lobe trapezoidal, with 2 pinnate inner setae, 2 distal setae, and 2 pinnate outer seta; all setae of different length and apical outermost is the longest. A secretory pore on anterior surface. Exopod twice as long as wide, with one short inner, 2 distal (innermost longest) and 2 outer setae, all pinnate.

Description.

Male (Fig. 9A). Body smaller and more slender than female. Body length 564 µm (n=6; range: 509-613 µm), measured from anterior margin of rostrum to posterior margin of caudal rami. Largest width measured at P2-bearing somite: 131 µm. Sexual dimorphism in antennule, P3-P4 endopod, P5 and P6.

Cephalothorax (Fig. 9A) with smooth posterior margin, with integumental sensilla. Urosome (Fig. 9 B–D) 6-segmented, comprised of P5-bearing somite, genital somite, and 4 free abdominal somites. Urosomites with spinules along posterior margin dorsally and ventrally. Anal somite with inner process on lateral margin.

Antennule (Fig. 10 D–E) 10-segmented; subchirocer with geniculation between segments 7 and 8. Segment 2 largest. Segment 5 not swollen. Aesthetasc on segments 5 and 10. Some elements on segments 7 and 8. Armature formula: 1-[1], 2-[10], 3-[8], 4-[2], 5-[6 + (1 + ae)], 6-[2], 7-[2 + 2 modified] 8-[3 modified], 9-[1], 10-[7 + acrothek]. Apical acrothek consisting of a small aesthetasc fused basally to 2 bare setae.

P3 (Fig. 10A). Setae on exopod modified. Endopod modified, 3-segmented; enp-1 with inner seta; enp-2 with well-developed inner apophysis; enp-3 with 2 apical setae.

P4 (Fig. 10B). Exp-3 setae modified. Enp-2 with 1 inner and 3 distal setae.

Fifth pair of legs (P5) (Fig. 10C) fused medially. Baseoendopod with outer setophore bearing the basal seta. Endopodal lobe with 2 distal pinnate setae, the outmost longest, large pore on anterior surface. Exopod about 2.6 times as long as wide, with 1 outer and 1 outer distal pinnate setae of similar length, 2 pinnate distal setae, the innermost longest, and a small outer pinnate seta.

P6 (Fig. 9B) asymmetrical, bearing 1 pinnate outer, 1 long naked and 1 short bipinnate inner setae on a cylindrical process, apically.

Etymology.

The species name refers to Tahoe Tessie, a cryptozoological creature which supposedly resides in Lake Tahoe. While some claim to have seen the mythical Tahoe Tessie, none until now have seen these non-mythical microscopic creatures of the sand.