Paramerina okigenga (Sasa)

Niitsuma, Hiromi, Suzuki, Risa & Kato, Hideaki, 2011, Review of the Japanese species of Paramerina (Diptera: Chironomidae: Tanypodinae), with a key to the known males, Zootaxa 2821, pp. 1-18 : 7-11

Paramerina okigenga (Sasa)

( Figures 15 –28)

Monopelopia okigenga Sasa, 1990: 141 .

Krenopelopia amaminova Sasa, 1990: 138 partim (male paratypes). Paramerina kurobekogata Sasa et Okazawa, 1992a: 64 . Syn. n. Paramerina yunouresia [nec Sasa, 1989]: Niitsuma 2005: 1053 fig. 16, 1–5. Paramerina divis a [nec Walker, 1856]: Kobayashi & Endo 2008: 52.

Material examined. Holotype of Monopelopia okigenga : male ( NSMT), labeled “No. 174: 94”, JAPAN: Okinawa, Okinawa Island, Genga River, 27.xi.1988 (adult emerged 20.ii.1989). Paratype of Monopelopia okigenga : 1 female ( NSMT), labeled “No. 174: 95”, same data as holotype. Paratypes of Krenopelopia amaminova : 2 males ( NSMT), labeled respectively, “No. 179: 64” and “No. 179: 66”, JAPAN: Kagoshima, Amami Island, Yakkachi River, 18.v.1989. Holotype of Paramerina kurobekogata : male ( NSMT), labeled “ Paramerina kurobeminuta K6 233, 96”, JAPAN: Toyama, Unazuki, Kurobe River, 22.viii.1991. Non-types. JAPAN: Fukushima, Hirono, Asami River, 1 pupa with larval exuviae (SUM-IC-T0308), 28.ix.2004; Fukushima, Iwaki, Yaguki, small stream, 1 larva (SUM-IC-T0309), 3.i.1997; 1 pupa with larval exuviae (SUM-IC-T0310), as previous except 15.viii.2002; 3 males with 3 pupal and 3 larval exuviae (SUM-IC-T0311–0313), as previous except 1.i.2008 (adults emerged 26.i– 1.ii.2008); 2 males with 1 pupal exuviae (SUM-IC-T0314, T0315), 1 female with pupal exuviae (SUM-IC-T0316), as previous except 14.viii.2008 (adults emerged 21.viii.2008); 7 males with 7 pupal and 7 larval exuviae (SUM-IC- T0317–0323), as previous except 19.iv.2009 (adults emerged 25–30.iv.2009); Kanagawa, Kiyokawa, Miyagase, small stream, 1 male and 1 female with 2 pupal and 2 larval exuviae (SUM-IC-T0324, T0325), and 1 larva (SUM- IC-T0326), 21.v.1993 (adults emerged 27.v and 3.vi.1993); 1 larva (SUM-IC-T0327), as previous except 30.ix.1993; 3 males and 1 female with 4 pupal and 4 larval exuviae (SUM-IC-T0328–0331), as previous except 23.ii.1994 (adults emerged 28.ii–6.iii.1994); 1 larva (SUM-IC-T0332), as previous except 26.v.1996; 1 female with pupal and larval exuviae (SUM-IC-T0333), as previous except 18.x.1998 (adult emerged 22.x.1998); 1 male with pupal and larval exuviae (SUM-IC-T0334), as previous except 3.x.1999 (adult emerged 15.x.1999); Shizuoka, Ashikubo, small stream, 1 male with pupal and larval exuviae (SUM-IC-T0335), 6.ii.1988 (adult emerged 10.iii.1998); Shizuoka, Ikawa, small stream, 1 larval exuviae (SUM-IC-T0336), 15.ix.1996; 1 male with pupal and larval exuviae (SUM-IC-T0337), 3 females with 3 pupal exuviae (SUM-IC-T0338–0340), and 1 larva (SUM-IC- T0341), as previous except 16.ix.2002 (adults emerged 13.ix–23.x.2002); Shizuoka, Uchimaki, Uchimaki River, 2 females with 2 pupal and 2 larval exuviae (SUM-IC-T0391, T0392), 16.v.2010 (adults emerged 26 and 27.v.2010); 1 male with pupal exuviae (SUM-IC-T0393), as previous except 29.v.2010 (adult emerged 12.vi.2010); 1 male with pupal and larval exuviae (SUM-IC-T0394), 2 females with 2 pupal and 1 larval exuviae (SUM-IC-T0395, T0396), as previous except 5.vi.2010 (adults emerged 10–15.vi.2010).

Description. Male (n = 25). Body length 1.9–3.3 (2.7, n = 21) mm.

Coloration. Thorax yellow with dark 4 scutal vittae, anepisternum II, preepisternum and postnotum ( Fig. 15 ). Abdomen yellow with dark bands; band narrow, occasionally absent, on tergite I, always absent on tergites II, V and IX, and broad on tergites III, IV, VI–VIII. Wing without pattern. Legs largely yellow.

Head. Temporals 11–24 in number, uniserial. AR 0.6–1.3. Clypeus rounded with 16–36 setae. Lengths of palpomeres 1–5 (in μm) 30–45 (37, n = 20), 38–75 (57, n = 20), 100–210 (153, n = 20), 115–190 (152, n = 20) and 195–325 (258, n = 20); Pm4 0.9–1.2 times as long as Pm3; Pm5 1.6–1.9 times as long as Pm4.

Thorax. Aps 1–6 in number, located laterally. Ac 23–53, biserial, evenly diverging posteriorly; Dc 13–36 including 1–2 Prs, bi- to multiserial; H 5–21; Pa 8–19, multiserial; Su 1. Scutellum with group of 5–24 short anterior setae and transverse row of 6–13 long posterior setae.

Wing ( Fig. 16 ). Length 1.3–2.6 (1.9, n = 21) mm. Squama with 12–37 setae; VR 0.83–0.89.

Legs. Spur of foretibia 38–55 (45, n = 21) μm long, with 3 or 4 lateral teeth; spurs of midtibia 53–73 (62, n = 21) and 25–43 (33, n = 21) μm long, with 2–4 and 2–3 lateral teeth, respectively; spurs of hind tibia 53–78 (65, n = 21) and 25–43 (32, n = 21) μm long, each with 2 or 3 lateral teeth; hind tibial comb consisting of 5 or 6 spines.

Pseudospurs present on ta1–3 or ta1–4 of all legs; claw apically pointed with 1 long basoventral spine. Lengths and proportions of leg segments as in Table 2.

TABLE 2. Lengths (in μm) and proportions of legs of Paramerina okigenga (Sasa) , male (n = 18) and female (n = 10). fe ti ta1 ta2 ta3 ta4 ta5 LR BR

Male

p1 505–889 526–990 434–838 293–556 202–414 141–253 81–131 0.82–0.93 3.8–5.7

(688) (741) (631) (408) (294) (187) (101)

p2 626–1091 475–869 495–879 273–475 171–303 111–192 71–111 1.01–1.17 4.9–7.3

(841) (648) (686) (374) (230) (149) (95)

p3 535–909 576–1162 495–909 283–545 212–414 152–273 81–131 0.78–0.92 5.5–7.4

(705) (845) (708) (411) (306) (200) (100)

Female

p1 455–808 485–859 394–697 232–465 162–354 111–202 71–121 0.81–0.89 (587) (621) (524) (332) (233) (150) (90) p2 596–980 455–818 475–758 222–404 131–242 91–161 71–101 0.93–1.07 (732) (603) (585) (301) (184) (124) (83) p3 495–859 545–1081 444–838 263–475 202–374 131–232 71–111 0.78–0.85 (627) (745) (604) (348) (264) (173) (89)

Hypopygium ( Fig. 17 ). Tergite IX without setae. Gonocoxite 120–208 (162, n = 21) μm long, 2.7–3.0 times as long as broad at middle. Gonostylus 80–140 (110, n = 21) μm long; HR 1.4–1.6. Phallapodeme conspicuously elongated, and its posterior tip reaching 0.42–0.66 from base of gonocoxite.

Female (n = 12). Body length 1.2–2.2 (1.6, n = 10) mm.

Coloration. Similar to male.

Head. Temporals 8–22 in number. Antenna with terminal flagellomere longer than preceding 2 flagellomeres together; AR 0.21–0.26. Clypeus with 12–43 setae. Lengths of palpomeres 1–5 (in μm) 25–45 (33, n = 7), 38–63 (48, n = 7), 100–165 (119, n = 7), 113–158 (127, n = 7) and 180–255 (214, n = 7); Pm4 1.0–1.2 times as long as Pm3; Pm5 1.6–1.9 times as long as Pm4.

Thorax. Aps 1–5 in number, Ac 25–53, Dc 14–54, H 14–36, Pa 11–32, Su 1. Scts composed of 7–27 short anterior and 6–13 long posterior setae.

Wing. Length 1.2–2.2 (1.6, n = 11) mm. Squama with 12–37 setae; VR 0.81–0.89.

Legs. Spur of foretibia 38–53 (42, n = 11) μm long, with 2–5 lateral teeth; spurs of midtibia 50–68 (58, n = 11) and 25–40 (31, n = 11) μm long, with 2–4 and 2–3 lateral teeth, respectively; spurs of hind tibia 50–70 (60, n = 11) and 23–40 (31, n = 11) μm long, each with 2 or 3 lateral teeth; hind tibial comb consisting of 4–6 spines. Lengths and proportions of leg segments as in Table 2.

Genitalia ( Fig. 18 ): Notum 75–120 (97, n = 5) μm long. Seminal capsule pale, oval, 53–70 (60, n = 6) μm long, and 45–63 (53, n = 6) μm wide. Segment X with 8–15 short setae on each side.

Pupa (n = 33). Body length 2.6–4.1 (3.2, n = 31) mm.

Coloration. Exuviae mostly brown. Abdomen dark on scar and apophyses; tergites III–VI pale posterolaterally.

Cephalothorax. Thoracic horn (Fig. 19) 163–275 (213, n = 30) μm long, 3.0–4.1 times as long as broad; corona 68–120 (97, n = 30) μm long, more or less triangular with rounded corners, occupying apical 0.41–0.51 of horn; plastron plate more or less oval, 33–63 (51, n = 30) μm long, 0.43–0.60 times as long as corona, and 4.0–9.0 times as long as width of its neck; respiratory atrium smooth or slightly rugged on surface, with well-developed apical diverticulum. Thoracic comb composed of 7–16 apically rounded tubercles.

Abdomen (Fig. 20). Shagreen consisting of weak and sparse spinules on sternites and tergites (Fig. 21), except sternite II with somewhat strong shagreen (Fig. 22). Segment VII with 4 LS-setae and 1 L-seta on each side, occasionally LS1-seta reduced to small setal mark; LS1-seta positioned 0.42–0.54 from anterior margin of segment. Segment VIII with 5 LS-setae on each side; LS1-seta positioned 0.24–0.30 from anterior margin of segment. Anal lobe 275–425 (340, n = 30) μm long, 3.0–3.6 times as long as wide, with 12–21 pale spines along outer boarder; anterior and posterior anal macrosetae located respectively 0.35–0.43 and 0.52–0.60 from anterior margin of anal lobe. Male genital sac 1.1–1.2 times as long as anal lobe.

FIGURES 19–28. Paramerina okigenga (Sasa) , pupa (19–22) and larva (23–28). 19, Thoracic horn with basal lobe; 20, abdominal segments VII–IX, dorsal view, left lateral setae omitted; 21, shagreen on posteromedial part of abdominal tergite IV; 22, shagreen on posteromedial part of abdominal sternite II; 23, head with chaetotaxy, dorsal view (R) and ventral view (L); 24, antenna; 25, mandible, seta subdentalis and ventrolateral setae omitted; 26, maxillary palp with apical stylets; 27, ligula and paraligula; 28, smaller claws of posterior parapod. Abbreviations: CP, coronal sensory pore; S1–11, cephalic setae 1–11; SSm, seta submenti; VP, ventral sensory pore.

Fourth instar larva (n = 32). Body length 4.2–5.4 (5.0, n = 5) mm.

Coloration. Head dark brown on posterior 1/3–2/3, and body entirely reddish when alive.

Head (Fig. 23). Length 470–677 (570, n = 14) μm; cephalic index 0.48–0.57. Dorsal cephalic setae S1–3 and S8 simple, S4–7 3- or 4-branched; S8 posteromedial to S7, and anterolateral to S5; dorsal sensory pore absent. Ventral cephalic seta S9 simple, S10 and SSm 3- or 4-branched; S10 posteromedial to S9, anteromedial to sensory pore, and these ventral setae and sensory pore all anterolateral to SSm; S9, S10 and SSm arranged almost in line. Antenna (Fig. 24) 0.49–0.54 times as long as head capsule; lengths of first to fourth segments (in μm) 168–255 (213, n = 17), 63– 80 (72, n = 17), 7–9 (8, n = 17) and 5–6 (5, n = 17); AR 2.0–3.0. First segment 8.3–11.9 times as long as its basal width, with ring organ positioned 0.58–0.67 from base; blade 70–90 (81, n = 12) μm long, reaching apex of segment 3; accessory blade 73–93 (83, n = 14) μm long, slightly longer than blade. Second segment 8.7–10.7 times as long as its basal width; style 10–12 (11, n = 12) μm long, nearly reaching apex of segment 4; peg sensillum 4–5 (5, n = 17) μm long. Mandible (Fig. 25) 75–115 (95, n = 21) μm long, 0.29–0.36 times as long as antenna, with apical tooth 2.3–2.6 times as long as basal width. Basal segment of maxillary palp (Fig. 26) subdivided into 2 parts, 35–55 (45, n = 18) μm in total length, and 3.9–5.0 times as long as its basal width; apical part 2.4–3.0 times as long as basal part. Ligula (Fig. 27) 68–93 (80, n = 17) μm long, 1.8–2.1 times as long as its toothed width, with granulose area occupying basal 0.17–0.25; median tooth 1.6–2.0 times as long as wide. Paraligula 30–43 (36, n = 17) μm long with fork positioned 0.46–0.63 from base; outer spine 2.5–4.0 times as long as inner spine. Pecten hypopharyngis with row of 12–17 teeth.

Body. Procercus 3.3–3.8 times as long as wide, with 7 anal setae; both lateral setae located respectively 0.36– 0.41 and 0.61–0.69 from base. Posterior parapod with 16 yellow and simple claws (Fig. 28); occasionally larger claws serrated along inner and/or outer margin.

Remarks. Sasa (1990) described Monopelopia okigenga on the basis of the holotype male and the paratype female, and noted (p. 141), “hind tibiae with only one terminal spur.” We re-examined these type specimens, and it was proved that the author overlooked the abdominal tergite IX without setae, the long and apically hooked phallapodemes in the male hypopygium, as well as the very small outer tibial spur on the hind leg. The species thus belongs to Paramerina , as pointed out by Kobayashi & Endo (2008).

The male mostly resembles that of the European P. d i v i s a in the presences of both the median and lateral scutal vittae, the wing without any marking, and the entirely yellow abdominal tergites I, II, V and IX, but may be separable from it by the low value of antennal ratio. The antennal ratio is 0.6–1.3 in P. okigenga , while 1.45–1.50 in P. divisa , according to Fittkau (1962). Also the larvae of these species are very similar to each other in the head capsule darkened posteriorly (see Rieradevall & Brooks 2001 for P. d i v i s a), but differences between both the pupae are distinct. The plastron plate of the thoracic horn is 0.43–0.60 times as long as the corona, and 4.0–8.3 times as long as the width of its neck in P. okigenga : while in P. d i v i s a, that is about 0.25 times as long as the corona, and slightly longer than the width of its neck, according to Zavȓel & Thienemann (1921, fig. 7B), Fittkau (1962, fig. 274) and Langton (1984, pl. 17a). In addition, the abdominal segment VII is armed with four pairs of LS-setae in P. o k i - genga, but with three pairs of LS-setae in P. d i v i s a ( Fittkau 1962, fig. 284b; Langton 1984, pl. 17a).

We re-examined also the holotype male of P. kurobekogata . The male is characterized by the low value (0.79) of antennal ratio, the distinct four scutal vittae, and the yellow abdominal tergites I, II, V and IX, as noted in its original description ( Sasa & Okazawa 1992a). The species is undoubtedly a junior synonym of P. okigenga .

Figures

FIGURES 15 – 18. Paramerina okigenga (Sasa), male (15 – 17) and female (18). 15, Thorax, showing marking pattern, dorsal view; 16, wing; 17, hypopygium, dorsal view; 18, genitalia, ventral view.