Parachironomus hazelriggi Spies, 2000

Orel, Oksana V., 2017, Two new species and new records of the genus Parachironomus Lenz, 1921 (Diptera, Chironomidae) from northern Russia, Zootaxa 4312 (3), pp. 531-546 : 535-536

Parachironomus hazelriggi Spies, 2000

( Figs 5–10 , 17–21 )

Parachironomus hazelriggi Spies, 2000: 133 , figs 5, 11.

Material. Four males, Russia, Chukotka Autonomous Region, Chaunskaia Guba, Chaun River , 17.vii.1978, leg. E. Makarchenko.

Male imago (n=1 to 4). See also Table 5.

Total length 4.8–5.2 mm.

Coloration. Scape brown; ground color of thorax pale yellow, mesonotal stripes and postnotum brown; abdomen and legs brown.

Head. Frontal tubercles absent. Temporal setae 30–35. Clypeus with 25–30 setae. Antenna 1218–1302 µm long. AR 2.63–2.81. Maxillary palpomeres 2–4 combined 664–704 µm long, their individual lengths (in µm): 64– 72; 160–192; 184–200; 232–256. Antenna length/palp length 1.76–2.09. Palp length/head width 1.09–1.17.

Thorax. Antepronotals 9–14, acrostichals 21–25, dorsocentrals 20–34, prealars 8–12, supraalars 1. Scutellum with 23–33 setae.

Wing. Length 2.60–2.64 mm. VR 1.09–1.13. R with 24–31, R1 with 21–25, R4+5 with 25–35 setae in distal 2/3, M1+2 without setae. Squama with 23–31 setae.

Legs. See Table 2. Each mid and hind tibia with 2 fused combs and 2 spurs (length 34–37 µm). BR P1 3.33– 3.75, BR P2 3.43–3.70. Hind tarsomeres lost from all 4 specimens.

continued.

Hypopygium ( Figs 5–10 , 17–21 ). Laterosternite IX with 3–4 setae. Anal tergite bands separate, with median longitudinal part. Anal point in dorsal view length 156–177 µm, at about apex width 14 µm; anal point in lateral view straight and narrow, the base width 37 µm, at about apex width 14 µm with wider, tapering basal half (length 68–78 µm) that carries microtrichia and 9–13 lateral to dorsal setae (from 4 specimens only 1 with 1–2 dorsal setae), and with parallel-sided, bare distal half. Portal setae (see Spies 2000) 2–4 on each side; if>2 setae, these are separated by distances at last equal to the diameter of their bases, if only 2 setae, the distance between them is 3-4 times the diameter of the bases. Transverse sternapodeme 95 µm long. Superior volsella (119–126 µm long) straight both in the dorsal and lateral views, little to moderately expanded at the base, apically with lamellar projection (10–14 µm) as wide as apex of volsella, with 1 terminal (44–51 µm) and 1 medial (34–54 µm) setae located in pits usually as wide as the volsella, the distance between them 6.8–14 µm ( Figs 5–8 ). Inferior volsella without distinct prominence to median or posterior, its microtrichia not elongate. Gonostylus 306–313 µm long, in dorsal and lateral views slightly curved, in the proximal part expanded (37–41 µm) and bears 8–15 latero-ventral setae, in dorsal view usually slightly expanded (34–41 µm) in distal half, in lateral view gonostylus more expanded (44 µm) at about middle and gradually tapers to the top, with a row of 7–8 distal-median setae ( Fig. 10 ). HR 0.54– 0.60.

Remarks. Far Eastern Palaearctic males of P. hazelriggi have AR 2.63–2.81, LR P1 1.24–1.31, whereas the reported Nearctic ranges are AR 2.13–2.56, LR P1 1.33–1.66 ( Spies 2000). All other morphological differences observed ( Table 5) are consistent with the respective body size ranges.

Distribution. Holarctic species. The new record from the Chaun River, Chukotka Peninsula (Russian Far East) is the first one from the Palaearctic region.

Figures

FIGURES 1 – 8. Adult males of P. aquilonis sp. n. (1 – 4) and P. hazelriggi. (5 – 8). 1, 5 — hypopygium, dorsal view; 2 – 4, 6 – 8 — variations in the structure of the superior volsellae (2, 7 – 8 — dorsal view, 3 – 4, 6 — lateral view). Scale bars 50 µm.

FIGURES 9 – 11. Hypopygium in lateral view of P. hazelriggi (from Spies 2000) (9), P. hazelriggi (our data) (10) and P. aquilonis sp. n. (11). Scale bars 50 µm.

FIGURES 17 – 21. Details of hypopygium structure of P. hazelriggi (our data) (17, 18 — dorsal view; 20 — ventral view; 19, 21 — lateral view). Scale bars 500 µm.