Arctodiamesa marinae, Makarchenko, Eugenyi A., 2005

Makarchenko, Eugenyi A., 2005, A new species of Arctodiamesa Makarchenko (Diptera: Chironomidae: Diamesinae) from the Russian Far East, with a key to known species of the genus, Zootaxa 1084, pp. 59-64 : 60-63

Arctodiamesa marinae sp. n.

( Figs. 1–17 )

Material. Holotype: male, Russia, Kedrovaya River, Kedrovaya Pad Nature Reserve, Khasansk District, Primorye Territory, N 43°05’ 874”, E 131°33’ 412”, 4.VI. 2005, light trap, leg. E. Makarchenko. Paratypes: 3 males reared from pupae, 4 pupae, 1 pupa reared from larva, 5 fourth­instar larvae, same data as holotype except 2–4.VI. 2005, leg. E. Makarchenko.

Male imago (n = 4, except when otherwise stated). Total length 3.9–4.3 mm. Wing length 3.12–3.28 mm. Total length/wing length 1.25–1.31. Coloration brown.

Head. Eyes hairy. Temporal setae including only 14–16 postorbitals, verticals absent. Clypeus with 6 setae. Antenna with 13 flagellomeres and well­developed plume; pedicel with 2 or 3 setae. Length of subapical seta of terminal flagellomere 40– 44 m. AR 1.29. Lengths (m) of palpomeres 1­5: 44–48: 108–120: 124–160: 124–160: 150–172; second palpomere with sensilla capitata (diameter about 4 m) in distal part. Head width/palp length 1.34.

Thorax. Antepronotum with 11–13 lateral setae. Acrostichals absent, dorsocentrals 16–21, prealars 13–16. Scutellum with 34–37 setae.

Wing. Anal lobe well developed. Squama with 41–43 setae. R with 12–15 setae, R1 with 2 campaniform sensillae and 8 or 9 setae, R4+5 with 2 or 3 setae subapically. R2+3 faint with 2 campaniform sensillae in basal part.

Legs. BR1 2.7, BR2 2.0, BR3 4.3. Spur of front tibia 92 m. Spurs of middle tibia 48 m and 40 m long, of hind tibia 76 m and 44 m long. Hind tibial comb with 10 setae. Middle ta1 with 2 pseudospurs 28 m long, hind ta1 with 2 pseudospurs 36 m long.

Lengths (m) and proportions of legs (n = 1): Hypopygium ( Figs. 1–4 ). Tergite IX with 30 setae and narrow, anal point 68 m long. Laterosternite IX with 12 setae. Transverse sternapodeme 144 m wide. Medial aedeagal lobe weakly sclerotized, with strong apical spines ( Fig. 4 ). Gonocoxite 284–288 m long, superior and inferior volsellae reduced. Gonostylus 156 m long, with rounded, wide (36–40 m) lobe in basal half and short projection in subapical part; megaseta 20 m long. HR 1.82–1.85.

Pupa (n = 4). Total length 4.9–5.5 mm. Coloration brownish. Exuviae grey or brownish grey.

Cephalothorax. Frontal tubercles low, with 252–256 m long setae. Thorax smooth and granulated. Pc­setae lengths (m): Pc 1 — 11–2 –116, Pc2 — 305–310, Pc3 — 124–128 ( Fig. 5 ). Dorsocentrals divided into 5–12 branches 16–36 m long ( Figs. 6–8 ).

Fourth­instar larva (n = 5). Coloration greenish. Total length 6.8–7.4 mm.

Head. Head capsule 0.40–0.46 mm long, 0.30–0.34 mm wide, light yellow. Labrum with simple S I–S IV setae and large lamellae ( Fig. 12 ). Premandible brown to light brown, distally with 6 or 7 teeth ( Fig. 13 ). Antenna yellow, large ring organ situated in basal quarter of first segment; antennal blade ending near base of fourth segment ( Fig. 16 ); AR 1.56–1.61. Lengths (m) of antennal segments 1–5: 65.1: 15.0: 13.4: 4.2: 3.3. Mandible dark brown or black in distal part; apical tooth longest; seta interna with 15–18 branches, seta subdentalis short and spinelike ( Fig. 14 ). Mentum with 1 median and 7 lateral pairs of teeth; median tooth 4.7–5.0 times broader than first lateral tooth ( Fig.17 ).

Abdomen. Procercus dark brown, slightly longer than wide, with 7 anal setae. Two dark brown subapical setae 208–232 m long.

Remarks. The male of A. marinae can be separated from other known species of Arctodiamesa by the shape of the gonostyli. The basally wide and rounded lobe, combined with the short, subapical projection, is characteristic. Larvae of A. marinae have six or seven teeth on the premandible, whereas the other species have only three. Arctodiamesa marinae also differs from the other species by the wide median tooth of the mentum. The pupae are similar to those of the previously described but unnamed Arctodiamesa sp. ( Makarchenko 1995), but can be distinguished by details of the tergite shagreen and the number of branches on the dorsocental setae of the thorax. Arctodiamesa marinae has 5–12 branches on each dorsocentral, whereas Arctodiamesa sp. has only 2–4 branches.

Etymology. The new species is named in honour of my wife Marina Makarchenko , who studies the taxonomy of the Orthocladiinae of the Russian Far East. She is a driving force in my chironomid investigations.

Distribution and biology. Arctodiamesa marinae is known only from the type locality in Kedrovaya Pad Nature reserve in the southern part of Primorye Territory of the Russian Far East. Pupae and larvae were collected in the middle reaches of the Kedrovaya River on small and medium­sized stones covered with green algae. The water temperature was 14°C at the time of collection.

Figures

FIGURES 1 – 4. Male of Arctodiamesa marinae sp. n. 1, hypopygium in dorsal view; 2, gonostylus deflected from gonocoxite; 3, gonostylus pressed to gonocoxite; 4, sternapodeme and medial aedeagal lobe. Scale bars = 50 µm.

FIGURES 5 – 17. Pupa (5 – 11) and larva (12 – 17) of Arctodiamesa marinae sp. n. 5, precorneals; 6 – 8, dorsocentrals of thorax; 9, tergite IV; 10, netlike surface of tergites; 11, tergite VIII and anal segment; 12, part of labrum; 13, premandible; 14, mandible; 15, procercus; 16, antenna; 17, mentum. Scale bars = 50 m for Figs. 5 – 8, 10; 200 m for Figs. 9, 11; 20 m for Figs. 12 – 17.