Demicryptochironomus (Demicryptochironomus) minus, Yan, Chuncai, Tang, Hongqu & Wang, Xinhua, 2005

Yan, Chuncai, Tang, Hongqu & Wang, Xinhua, 2005, Demicryptochironomus Lenz from China (Diptera: Chironomidae), Zootaxa 910, pp. 1-31 : 4-14

Demicryptochironomus (Demicryptochironomus) minus sp. n. ( Figs. 2 A–E)

Type material: Holotype male, CHINA: Shanxi Province, Zhouzhi County, Banfangzi Town, 9 VIII. 1994, X. Wang (BDN no. 03929). Paratype CHINA: 2 males, Zhejiang Province, Qingyuan County, Baishanzu, Chegen. 13. VII. 1994. X. Wang; 2 males, Guizhou Province, Fanjing Mountain Natural Conservation, Heiwan Town, 3. VI. 2002, B. Ji., light trap; 2 males, as for holotype.

Etymology: From Latin minus , bare, referring to the bare inferior volsella except for the long apical seta.

Male imago (n = 7, unless otherwise stated)

Total length 3.85–4.18, 4.03 mm. Wing length 1.75–2.15, 2.01 mm. Total length/wing length 1.88–2.20, 2.01. Wing length/length of profemur 1.91–2.23, 2.03.

Coloration: Thorax yellowish brown, scutellum and dorsum of scutum light yellow, legs yellowish brown except dark brown fore tibiae and tarsi. Abdomen ( Fig. 2 B) yellowish brown, with posterior 1/4 of tergites II–VI dark brown or with dark brown spots, tergite IX and hypopygium dark brown, remainder of tergites yellowish green.

Head: AR 1.37–1.90, 1.68 (5), Ultimate flagellomere 590–800, 718 m long. Frontal tubercles present or absent; if present, cylindrical, 25 µm long or rounded, 5–6 µm in diameter. Temporal 13–22, 18 setae (6), including 2–6, 4 inner verticals; 6–12, 9 outer verticals; and 4–6, 5 postorbitals. Clypeus with 11–14, 12 setae. Tentorium 130–160, 147 µm long, 32–50, 43 µm wide. Palpomere lengths (in µm): 38–52, 43; 80–98, 91; 165–200, 178; 123–143, 134; 205–257, 234.

Thorax: Antepronotals 1–6, 4 (6), dorsocentrals 7–14, 10, acrostichals 5–10, 8, prealars 4–5, 4. Scutellum with 11–15, 13 setae.

Wing ( Fig. 2 A): VR 1.16–1.24, 1.20; R with 19–26, 22 setae; R1 with 12–18, 15 setae; R4+5 with 12–19, 14 setae. Brachiolum with 2 setae. Squama with 6–15, 11 setae. Anal lobe well developed.

Legs: Front tibia with 2 subapical setae, 130–150, 139 µm and 140–163, 150 µm long; spur of middle tibia 15–25, 23 µm; 20–38, 30 m long, comb with 30–40, 35 teeth, 10–12, 11 µm long; spur of hind tibia 25–32, 26 µm; 30–45, 35 µm long, comb with 46–56, 51 teeth, 10–12, 12 µm long. Tarsus 1 of mid legs with 0–1, 1 sensilla chaetica. Lengths (in µm) and proportions of legs:

Hypopygium ( Figs. 2 C–E): Anal point 65–90, 74 (6) µm long, widened medially, with ridges at base extending to tergite IX and with short lateral setae; basal part of anal point forming wedge on ninth tergite; anal point apically rounded. Tergite IX with 14–18, 16 setae on margin of anal point. Laterosternite IX with 3–4, 4 setae. Anal tergite bands Vshaped. Phallapodeme 75–93, 85 µm long. Transverse sternapodeme 25–53, 37 µm long. Superior volsella represented by two small tubercles bearing two long apical setae and covered by microtrichia. Inferior volsella bare except for 1 long apical seta. Gonocoxite 135–143, 140 µm long, inner margins forming blunt angle in middle. Gonostylus 153– 170, 162 µm long, widest at about basal 1/3, inner margin nearly straight, without distinct longitudinal keel, bearing 9–14, 12 setae in two rows on inner margin. HR 0.81–0.90, 0.86; HV 2.32–2.75, 2.49.

Distribution: This species is widespread in 3 Oriental Chinese provinces.

Remarks: The new species is easily distinguished from known species in the genus by the dark brown bands or spots present on tergites II–VI, superior volsella represented by two small tubercles bearing two long apical setae and covered with microtrichia, and inferior volsella bare except for a long apical seta.

Demicryptochironomus (Demicryptochironomus) pannus sp. n. ( Figs. 3 A–D)

Type material: Holotype male, CHINA: Yunnan Province, Lijiang County, Shigu Town, Chongjiang River. 1850 m. 25 V. 1996, X. Wang (BDN no. 10632). Paratype CHINA: 1 male, Guizhou Province, Fanjing Mountain Natural Conservation, Huixiangping, 1. VI. 2002, B. Ji; 2 males as for holotype.

Etymology: From Latin pannus , patch, referring to the patch­like superior volsella.

Diagnostic characters: The new species is similar to D. (D.) vulneratus (Zetterstedt, 1838) in the bilobed superior volsella. It can be separated by the small, patch­like superior volsella, bearing only two long setae not extended beyond the margin of the gonostylus, and the gonostylus nearly parallel­sided and apically rounded.

Male imago (n = 4, except when otherwise stated)

Total length 4.38–4.78, 4.52 mm. Wing length 2.35–2.55, 2.42 mm. Total length/wing length 1.86–1.87, 1.87. Wing length/length of profemur 1.92–2.36, 2.22.

Coloration: Thorax brown or dark brown, scutellum and dorsum of scutum light yellow. Abdomen yellowish green or brownish green; tergite IX and hypopygium dark brown. Femora and tarsi of fore legs dark brown; tarsi of mid and hind legs brown; remainder of fore, mid and hind legs yellowish green.

Head: AR 2.32–2.39, 2.36. Ultimate flagellomere 870–910, 890 µm long. Frontal tubercles present or absent, when present, cylindrical, 25 µm long, 7 µm wide, slightly swollen at apex. Temporal 13–19, 16 setae (3), including 3–6, 4 inner verticals; 5–9, 6 outer verticals; and 5–9, 6 postorbitals. Clypeus with 10–18, 14 setae. Tentorium 138–175, 158 µm long, 45–55, 49 µm wide. Palpomere lengths (in µm): 45–48, 47; 68–75, 73; 168– 212, 188; 168–215, 187; 240–297, 267.

Thorax: Antepronotals 2–6, 4, dorsocentrals 10–13, 11, acrostichals 8–12, 9, prealars 5–7, 6. Scutellum with 11–15, 13 setae.

Wing ( Fig. 3 A): VR 1.09–1.20, 1.14; R with 17–25, 20 setae; R1 with 11–24, 14 setae; R4+5 with 9–35, 20 setae. Brachiolum with 2–3, 3 setae. Squama with 11–16, 14 setae. Anal lobe well developed.

Legs: Front tibia with 2 subapical setae, 118–143, 131 µm and 120–163, 145 µm long; spur of middle tibia 25–30, 29 µm; 30–42, 37 µm long, comb with 30–41, 37 teeth, 9–12, 11 µm long; spur of hind tibia 22–35, 31 µm; 38–47, 42 µm long, comb with 45–58, 51 teeth, 10–13, 12 µm long. Tarsus 1 of mid legs with 1–2, 2 sensilla chaetica. Lengths (in µm) and proportions of legs:

Hypopygium ( Figs. 3 B–D): Anal point nearly parallel­sided, 78–92, 87 µm long, 12– 25, 18 µm wide at base, 5–13, 10 µm wide at apex, with Y­shaped ridges at base of anal point extending to tergite IX and with short lateral setae. Tergite IX with 20–30, 25 setae. Laterosternite IX with 4–5, 4 setae. Anal tergite bands slightly U­shaped. Phallapodeme 75–100, 92 µm long. Transverse sternapodeme forming sharp angle at apex. Superior volsella ( Fig. 3 B) much reduced, patch­like not extending beyond margins of gonocoxite, bilobed, bearing two long apical setae and microtrichia. Gonocoxite 130–140, 138 µm long. Gonostylus 170–187, 178 µm long, inner margin concave, with a strong longitudinal keel, bearing 18–26, 22 setae in 2 or 3 rows on inner margin. HR 0.74–0.82, 0.78; HV 2.34–2.69, 2.55.

Distribution: This species was collected with light traps in the subtropical mountain areas of two southern Chinese provinces (Oriental China).

Demicryptochironomus (Demicryptochironomus) vulneratus (Zetterstedt) ( Figs. 4A–D )

Chironomus vulneratus Zetterstedt 1838: 838 ; Edwards 1929: 390.

Chironomus atriforceps Goetghebuer 1928: 84 ; Edwards 1929: 390.

Demicryptochironomus ploenensis Lenz 1960: 450 ; Fittkau and Reiss 1978: 406.

Demicryptochironomus vulneratus Lenz 1954 –1962: 222; Lehmann 1971: 497; Saether 1977: 131; Pinder 1978: 120; Pankratova 1983: 186; Pinder & Reiss 1983: 310; Nocentini 1985: 108; Wang et al. 1994: 208; Dutta et al. 1996: 271; Zorina 2004: 230.

Material examined: 11 males: 1 male, Zhejiang Province, Qingyuan County, Baishanzu, Chameiyu, 1200m, 15. VII. 1994, X. Wang; 1 male, Zhejiang Province, Tianmu Mountain Natural Conservation, Houshanmen, 11. VIII. 1998, light trap, X. Wang; 2 males, Fujian Province, Wuyi Mountain Natural Conservation, Tongmu, Qiliqiao village, 28. IX. 1993, light trap, X. Wang; 1 male, Fujian Province, Wuyi Mountain Natural Conservation, Tongmu, 27. IX. 1993, sweep net, X. Wang; 1 male, Shandong Province, Maoping County, Nan village, 28. VIII. 1988, sweep net, X. Wang. 1 male; Henan Province, Luanchuan County, Longyuwan, 1000m, 11. XII. 1996, light trap, J. Li; 1 male, Guizhou Province, Maolan County, Sancha river, 420m, 29. VII. 1995, light trap, W. Bu; 1 male, Shanxi Province, Zhouzhi County, Banfangzi, 9. VIII. 1994, light trap, B. Ji; 2 males, Shanxi Province, Ningshan County, Xunyangba, 16. XIII. 1994, sweep net, W. Bu.

Male imago (n = 11, except when otherwise stated)

Total length 3.33–4.30, 3.82 mm. Wing length 1.86–2.38, 2.03 mm. Total length/wing length 1.74–2.02, 1.88. Wing length/length of profemur 1.88–2.27, 2.05.

Coloration: Thorax dark brown to yellowish green, scutellum lighter yellowish. Femora or tarsus 1 of front leg dark brown, remainder of front leg lighter brown, mid and hind legs lighter brown. Abdomen yellowish green to brown.

Head: AR 1.71–2.69, 2.17 (10). Ultimate flagellomere 600–890, 775 µm long. Frontal tubercles present or absent, if present, 18 µm long, divided into three semiglobular parts by two constrictions. Temporal setae 11–19, 16, including 2–4, 3 inner verticals; 5–10, 8 outer verticals; and 3–8, 5 postorbitals. Clypeus with 11–20, 16 setae. Tentorium 120–163, 145 µm long, 35–55, 44 µm wide. Palpomere lengths (in µm): 38–50, 44; 50–75, 60; 130– 192, 169; 117–205, 173; 205–302, 257.

Thorax: Antepronotals 1–4, 2 (3), dorsocentrals 8–13, 10, acrostichals 9–13, 11, prealars 4–6, 5. Scutellum with 9–21, 12 setae.

Wing ( Fig. 4A ): VR 1.10–1.16, 1.14; R with 18–25, 21 setae; R1 with 12–22, 16 setae; R4+5 with 18–30, 25 setae. Brachiolum with 2–3, 2 setae. Squama with 9–14, 11 (9) setae. Anal lobe well developed.

Legs: Front tibia with 2 subapical setae, 117–150, 137 µm; 150–175, 158 µm long, spur of middle tibia 20–38, 29 µm; 37–50, 43 µm long, comb with 31–60, 44 teeth, 10–12, 11 µm long; spur of hind tibia 20–38, 29 µm; 38–55, 46 µmlong, comb with 46–63, 54 teeth, 10–13, 12 µm long. Tarsus 1 of mid leg with sensilla chaetica 1–3, 2. Lengths (in µm) and proportions of legs:

Hypopygium ( Figs. 4B–D ): Tergite IX with 20–36, 26 setae beside ridges. Laterosternite IX with 3–8, 6 setae. Anal tergite bands U–shaped. Anal point nearly parallel–sided, 88–105, 95 µm long, 10–20, 13 µm wide at base, 4–12, 8 µm wide at apex, with V–shaped lateral ridges extending to tergite IX from base. Phallapodeme 75–112, 96 µm long. Transverse sternapodeme 25–55, 43 µm long. Superior volsella ( Fig. 4B ) bilobed apically, digitiform, with microtrichia at base, with 2 or 3 apical setae. Gonocoxite 107–137, 127 µm long; inner margins forming blunt angle in middle. Gonostylus 155–195, 177 µm long, widest at about basal 1/3, inner margin concave, with strong longitudinal keel, bearing 19– 25, 22 setae in two rows on inner margin. HR 0.61–0.78, 0.72, HV 1.90–2.41, 2.16.

Fourth–instar larva (n = 2, except when otherwise stated)

Material examined: 1 larva, Gansu Province, Wen County, Yangga Mountain 5. VII. 2001, 1955m, R. Zhang; 1 larva, Fujian Province, Jianning City, Wuyi Mountain Natural Conservation, 23. IX. 2002, Z. Liu.

Median­sized species, total length 5.8–7.27 mm, white in alcohol. Head capsule pale yellow, posterior occipital region pale. Head capsule 260–290 µm wide, 320–350 µm long, cephalic index (W/L) 0.81–0.83.

Antenna ( Fig. 4E ): Total length 193–198 µm long, about 0.61 times as long as head. 7–segmented, each segment length (in µm): 75–80, 78; 13–17, 15; 28–30, 29; 23–25, 24; 15–15, 15; 4; 3. AR = 0.80–0.83, 0.81. Basal segment 28–32, 30 µm wide, ratio (L/W): 2.46–2.58, 2.52. Ring organ located 2/3 of basal segment, 6–7, 7 µm in diameter, distance from base 50–55, 54 µm long. Second antennal segment relatively short, about as long as wide (width: 12.5–15, 13 µm). Segment 2 ratio (L/W): 0.83–1.2, 0.96. Blade situated at 2/ 3 of third segment, 45 µm long, extending to base of sixth segment. Accessory blade on apex of third segment, 7.5–10, 8 µm long, not reaching middle part of 4th segment. Style located at apex of fifth segment, about as long as sixth segment.

Labrum: SI hair­like, small. SII simple and strong, blade­like. SIV divided into 3 segments, each segment length (in µm) 13, 12, 7.5 (n = 1). Premandible ( Fig. 4F ) with 4 teeth, basal 2 broad and stout, apical tooth long and slender. Total length of premandible 75–80, 76 µm

Mandible ( Fig. 4G ): Total length 112–118, 116 m long. With 1 apical tooth and two sharp inner teeth. Apical tooth 25 µm long, combined width of two inner teeth 13–15 µm, only about 1/2 length of apical tooth. Seta subdentalis 6–8, 7 m long. Seta interna with three long blade­like branches. Pecten mandibularis with 2–3 short branches, which do not extend beyond inner margin.

Mentum ( Fig. 4I ): 95–100 µm wide, with 7 pairs of dark brown lateral teeth and 1 semicircular pale median tooth. Each half of sclerotized lateral teeth 45 µm wide, median pale tooth 35–38, 37 µm wide, each basal corner often with small dark area. Ventromental plate slender, 150–170, 162 µm long, with numerous striae; distance between ventromental plates 45–52 µm.

Maxilla ( Fig. 4H ): Maxillary palp with basal segment about 3 times as long as wide (length 45–52 µm; width 16–18 µm). Ring organ located in middle. Distal part with 4–6 short blades, b sensillum with ratio of basal segment to distal part about 6:1.

Abdomen: Posterior parapods 200 µm long, 140 µm wide. Procercus 30 µm high, 20 µm wide, with 8 anal setae, 440 µm long. Supraanal seta 230 µm long, longer than posterior parapods. Two pairs of conical anal tubules, upper pair smaller than lower pair.

Distribution: This species is widespread in the Palaearctic and Oriental Regions. It occurs in both Palaearctic and Oriental China.

Remarks: This species was described by Zetterstedt (1838) as Chironomus vulneratus . Lehmann (1971) transferred it to the genus Demicryptochironomus ; Saether (1977) agreed with him. According to the literature ( Lehmann 1971, Saether 1977, Pinder 1978, Wang et al. 1994, Dutta et al. 1996) and the Chinese material, the species lacks an inferior volsella, but Zorina (2004) mentioned the presence of an inferior volsella. Dutta et al. (1996) gave some diagnostic features of the species. They proposed D. (D.) chuzequartus Sasa 1984 as a synonym of the present species, but they had not seen type material.

The larval material from China presumed to belong to D. (D.) vulneratus was collected from a clear brook with sandy substratum; the larval color when alive was white. According to Pinder & Reiss (1983) and Nocentini (1985), the predaceous larvae of Demicryptochironomus commonly live in still waters and also can be found in lotic waters. Some minor differences between the Chinese specimens and the description of D. vulneratus by Pankratova (1983) from Russia and Nocentini (1985) from Italy are found in the antennal blade extension and in the length of the last three segments. In the Russian and Chinese specimens, the blade extends to the apex of the fifth segment, whereas in the Italian specimens it extends only to the apex of the fourth. As for the last three antennal segments, Pankratova (1983) mentioned that the fifth segment was subequal in length to the combined lengths of segments 6 and 7, whereas in the Italian (based on the drawing by Nocentini) and Chinese specimens, it appears that the fifth segment is longer than the combined length of segments 6 and 7.

Figures

FIGURE 2. Demicryptochironomus (Demicryptochironomus) minus sp. n. A. Wing. B. Abdomen. C. Superior volsella and inferior volsella. D. Dorsal view of hypopygium. E. Ventral view of hypopygium.

FIGURE 3. Demicryptochironomus (Demicryptochironomus) pannus sp. n. A. Wing. B. Superior volsella. C. Dorsal view of hypopygium. D. Ventral view of hypopygium.

FIGURE 4 A – D. Demicryptochironomus (Demicryptochironomus) vulneratus (Zetterstedt), Chinese specimen. A. Wing. B. Superior volsella. C. Dorsal view of hypopygium. D. Ventral view of hypopygium.