Chirundina Giesbrecht, 1895
Taxonomic description:
Female. Total length slightly less than 4.00 and to 5.50 mm. Cephalothorax 3-4 times longer than abdomen. Cephalon and Th1, as well as Th4-Th5 fused, often line of fusion visible. Rostrum present, well developed, one-pointed. Crest present or absent. Posterior Th5 corners symmetrical, rounded, or slightly prolonged, often with small knob, or tooth at the top. Genital segment symmetrical, the widest in its posterior half. Length and width of caudal rami are nearly equal. Posterior border of Abd2-3 with rows of minute spinules. A1 24-segmented, longer than cephalothorax, often reaching the end of caudal rami. Re A2 1.5-2.0 times longer than Ri, Re1 A2 with 1, Re2 A2 with 3 setae, Re3-Re6 with 1 long seta each, Re7 with 1 medial and 3 terminal setae; Ri1 A2 with 2 setae distally, Ri2 A2 with 8 setae on the internal and 6-7 setae on external lobes; coxopodite with 1 seta, basipodite with 2 setae. Md palp base with 3 setae, Ri1 Md with 2, Ri2 Md with 10 (9 terminal and 1 posterior) setae. Mx1 with 14 setae on gnathobase (9 claw-like terminal, 1 thin anterior and 4 on the posterior surface), 5 and 4 setae on the second and third internal lobes correspondingly, 5 on protopodite near Ri base, 15 on Ri, 11 on Re and 9 on external lobe. Mx2 with thickened spines on fourth and fifth endites. Mxp with 1 seta in proximal part of the segment, with 2, 3 and 3 setae (looking from proximal to distal) on protopodite; distal setae group with a small knob; Ri1 Mxp about twice as long as protopodite and supplied with "lamella" along external surface of segment. P1 with complete, or incomplete separation between Re1-Re2. External spine on Re1 present, or absent. P2 with one-segmented, or indistinct 2-segmented Ri. All other rami of swimming legs 3-segmented.
Male. Total length 3.75-5.20 mm. Cephalothorax about 3-4 times longer than abdomen. Cephalon usually with crest, but much lower than in female. Posterior Th5 corners rounded. A1 right 20-, left 21-segmented. Re1 A2 without setae, Re2 A2 with 1 seta. Md palp base without setae, Ri1 Md with 1 seta, Ri2 Md with 9 setae. Mx1 setation, as well as that of Mx2 rudimentary. Mxp close to that in Undeuchaeta. Segmentation and setation of P1-P4 as in female, only the spine on Re1 P1 may be shorter than in female. P5 biramous, with one-segmented Ri. Left Re P5 3-, right 2-segmented. P5 very close to that in Undeuchaeta.
Remarks. Tanaka (1969) described monotypic genus Wilsonidius and recorded that its single species W. alaskaensis is close to Undeuchaeta species. It seems that W. alaskaensis should rather be placed in genus Chirundina (Markhaseva, 1996). The only distinction of W. alaskaensis from other Chirundina species is the absence of crest on cephalon. In Aetideidae however, presence, or absence of crest is a character that may appear and disappear within one genus (Euchirella , Aetideus , Aetideopsis , etc.).
Type species: Chirundina streetsii Giesbrecht, 1895, by monotypy.
The genus Chirundina includes 3 species.
Chirundina alaskaensis (Tanaka, 1969)(male unknown)
Chirundina indica Sewell, 1929
Chirundina streetsii Giesbrecht, 1895