Paramerina togavicea (Sasa et Okazawa)

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 : 11-16

Paramerina togavicea (Sasa et Okazawa)

( Figures 29–41 )

Pentaneura divisa [nec Walker, 1856]: Tokunaga 1937a: 53, 1937b: 97. Paramerina divisa [nec Walker, 1856]: Sasa & Hasegawa 1988: 252; Kobayashi & Endo 2008: 52.? Paramerina divisa [nec Walker, 1856]: Fittkau 1962: 327.

Krenopelopia togavicea Sasa et Okazawa, 1992b: 213 .

Material examined. Holotype of Krenopelopia togavicea : male ( NSMT), labeled, “No. 188: 56”, JAPAN: Toyama, Toga, Toga River, 18.vii.1990. Non-types. JAPAN: Okinawa, Okinawa Island, Lake Ryutan, 5 males, 1 female, and 2 pupal exuviae ( NSMT), labeled respectively, “ Paramerina divisa No. 65: 35a, b, 36a, 42, 43, 36b, 37a, b ”, 7.xii.1981; Fukushima, Hirono, Asami River, 1 male with pupal and larval exuviae (SUM-IC-T0342), 15.viii.2001 (adult emerged 21.viii.2001); 1 male and 1 female with 2 pupal and 2 larval exuviae (SUM-IC-T0343, T0344), as previous except 5.v.2002 (adults emerged 11 and 15.v.2002); Fukushima, Iwaki, Yaguki, small stream, 3 males and 1 female with 4 pupal and 4 larval exuviae (SUM-IC-T0345–0348), 15.viii.2001 (adults emerged 26– 28.viii.2001); 1 female with pupal exuviae (SUM-IC-T0349), as previous except 14.viii.2008 (adult emerged 25.viii.2008); Kanagawa, Kiyokawa, Miyagase, small stream, 1 larva (SUM-IC-T0350), 14.vi.1998; 7 males with 7 pupal and 7 larval exuviae (SUM-IC-T0351–0357), 1 female with pupal exuviae (SUM-IC-T0358), and 1 larva (SUM-IC-T0359), as previous except 13.vi.1999 (adults emerged 15–29.vi.1999); 1 male with pupal and larval exuviae (SUM-IC-T0360), as previous except 3.x.1999 (adult emerged 15.x.1999); Shizuoka, Shimo, Kujiragaike, 2 larvae (SUM-IC-T0361, T0362), 30.xi.1987; Shizuoka, Ashikubo, small stream, 1 male with pupal and larval exuviae (SUM-IC-T0363), 20.ix.1990 (adult emerged 27.ix.1990); Shizuoka, Yokosawa, Abe River, 1 male and 2 females with 3 pupal and 3 larval exuviae (SUM-IC-T0364–0366), 29.viii.1999 (adults emerged 3–9.ix.1999); Shizuoka, Udo Hills, small stream, 3 larvae (SUM-IC-T0367–0369), 4.vi.1984; Shizuoka, Shimizu, Yanbara, small stream, 1 female with pupal exuviae (SUM-IC-T0370), and 2 larvae (SUM-IC-T0371, T0372), 23.vii.2008 (adult emerged 30.vii.2008); Shizuoka, Uchimaki, Uchimaki River, 2 larvae (SUM-IC-T0389, T0390), 5.vi.2010; Shizuoka, Hamakita, Hainoki River, 1 male with pupal and larval exuviae (SUM-IC-T0373), 8.ii.2003 (adult emerged 9.ii.2003).

Description. Male (n = 22). Body length 2.4–3.4 (2.8, n = 16) mm.

Coloration. Thorax ( Fig. 29 ) mostly pale yellow. Lateral scutal vittae pale brown, with dark markings anteriorly and posteriorly; but median vittae indistinct from thoracic pale yellow ground color; prescutellar area with dark marking along median line. Anepisternum II, preepisternum and postnotum brown. Abdomen pale yellow with dark bands; band broad on tergites III, IV, VI–VIII, and absent on tergites I, II, V. Wing without pattern. Legs largely pale yellow.

Head. Temporals 11–19 in number, uniserial. AR 1.3–1.8. Clypeus rounded with 14–23 setae. Lengths of palpomeres 1–5 (in μm) 35–45 (39, n = 12), 55–75 (61, n = 12), 130–183 (166, n = 12), 135–180 (163, n = 12) and 220–313 (260, n = 12); Pm4 0.9–1.0 times as long as Pm3; Pm5 1.4–1.8 times as long as Pm4.

Thorax. Aps 1–4 in number, located laterally. Ac 28–44, biserial, evenly diverging posteriorly; Dc 11–26 including 1–4 Prs, uni- or biserial; H 6–13; Pa 9–17, multiserial; Su 1. Scutellum with group of 7–19 short anterior setae and transverse row of 8–12 long posterior setae.

Wing ( Fig. 30 ). Length 1.6–2.4 (1.9, n = 16) mm. Squama with 20–35 setae; VR 0.85–0.92.

Legs. Spur of foretibia 33–45 (40, n = 16) μm long, with 4–6 lateral teeth; spurs of midtibia 55–68 (62, n = 16) and 25–39 (34, n = 16) μm long, with 4–5 and 3–4 lateral teeth, respectively; spurs of hind tibia 55–73 (67, n = 16) and 28–40 (35, n = 16) μm long, each with 3 or 4 lateral teeth; hind tibial comb consisting of 5–7 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 3.

Hypopygium ( Fig. 31 ). Gonocoxite 148–188 (162, n = 16) μm long and 2.7–2.9 times as long as broad at middle. Gonostylus 118–153 (131, n = 16) μm long; HR 1.2–1.3. Phallapodeme conspicuously elongated, and its posterior tip reaching 0.48–0.55 from base of gonocoxite.

Female (n = 8). Body length 1.5–2.1 (1.7, n = 5) mm.

Coloration. Similar to male.

Head. Temporals 15–20 in number. Antenna with terminal flagellomere longer than preceding 2 flagellomeres together; AR 0.24–0.27. Clypeus with 22–34 setae. Lengths of palpomeres 1–5 (in μm) 38–50 (44, n = 4), 55–70 (61, n = 4), 145–175 (158, n = 4), 140–180 (156, n = 4) and 225–283 (248, n = 4); Pm4 almost as long as Pm3; Pm5 1.5–1.8 times as long as Pm4.

Thorax. Aps 2–3 in number, Ac 31–45, Dc 23–39, H 16–23, Pa 13–21, Su 1. Scts composed of 18–25 short anterior and 9–12 long posterior setae.

Wing. Length 1.4–1.9 (1.6, n = 6) mm. Squama with 20–37 setae; VR 0.85–0.91.

Legs. Spur of foretibia 35–45 (39, n = 7) μm long, with 4 or 5 lateral teeth; spurs of midtibia 50–63 (57, n = 7) and 30–38 (33, n = 7) μm long, each with 3 or 4 lateral teeth; spurs of hind tibia 60–70 (64, n = 7) and 33–35 (33, n = 7) μm long, with 3–4 and 2–3 lateral teeth, respectively; hind tibial comb consisting of 6 or 7 spines. Lengths and proportions of leg segments as in Table 3.

Genitalia ( Fig. 32 ). Notum 90–113 (97, n = 5) μm long. Seminal capsule pale, 68–73 (70, n = 3) μm long and 53–60 (56, n = 3) μm wide. Segment X with 7–13 short setae on each side.

TABLE 3. Lengths (in μm) and proportions of legs of Paramerina togavicea (Sasa et Okazawa) , male (n = 16) and female (n = 7). fe ti ta1 ta2 ta3 ta4 ta5 LR BR

Male

p1 616–828 616–960 465–707 343–465 212–313 141–202 81–111 0.71–0.78 3.8–5.3

(703) (828) (621) (413) (285) (179) (100)

p2 697–980 556–859 495–747 283–394 172–232 121–162 81–101 0.81–0.92 5.4–8.7

(834) (734) (646) (343) (206) (139) (90)

p3 586–828 697–1172 596–879 354–515 242–354 152–222 81–111 0.75–0.86 6.6–7.9

(698) (960) (756) (434) (301) (193) (101)

Female

p1 545–707 616–848 495–667 283–404 202–283 121–162 81–101 0.76–0.81 (613) (714) (560) (341) (233) (141) (91) p2 667–899 616–848 515–687 212–343 152–212 111–152 76–101 0.81–0.88 (759) (708) (590) (296) (189) (127) (87) p3 566–768 788–1091 576–788 323–404 232–323 141–202 81–111 0.72–0.74 (659) (895) (652) (368) (271) (170) (96)

Pupa (n = 25). Body length 2.9–4.0 (3.4, n = 23) mm.

Coloration. Exuviae generally brown. Abdomen brown with scar and apophyses darkened; occasionally tergites III–VI pale posterolaterally.

Cephalothorax. Thoracic horn ( Fig. 33 ) 188–290 (214, n = 23) μm long, 3.4–4.8 times as long as broad, with oval corona occupying its apical 0.16–0.44; plastron plate oval, 25–50 (39, n = 23) μm long, 0.42–0.56 times as long as corona, and 3.3–5.7 times as long as width of its neck; respiratory atrium relatively smooth on surface, with well-developed apical diverticulum. Thoracic comb composed of 8–13 apically rounded tubercles.

Abdomen ( Fig. 34 ). Shagreen spinules dense and strong on sternite II ( Fig. 35 ), sparse and weak on other sternites and tergites ( Fig. 36 ). Segment VII with 4 LS-setae and 1 L-seta on each side; LS1-seta positioned 0.41–0.51 from anterior margin of segment. Segment VIII with 5 LS-setae on each side; LS1-seta positioned 0.21–0.28 from anterior margin of segment. Anal lobe 295–395 (338, n = 23) μm long, 3.2–3.7 times as long as wide, with 15–23 pale spines along outer boarder; anterior and posterior anal macrosetae located respectively 0.36–0.45 and 0.50– 0.56 from anterior margin of anal lobe. Male genital sac 1.2–1.3 times as long as anal lobe.

Fourth instar larva (n = 31). Body length 3.2–6.3 (5.0, n = 9) mm.

Coloration. Head dark brown on postoccipital margin, and body generally reddish when alive.

Head ( Fig. 37 ). Length 556–576 (564, n = 10) μm; cephalic index 0.49–0.54. Dorsal cephalic setae S1–3 and S8 simple, S4–7 3- or 4-branched; S8 directly mesal to S7, and anterolateral to S5; dorsal ssensory pore absent. Ventral cephalic setae S9 and S10 simple, and SSm 3- or 4-branched; S10 posteromedial to S9, directly anterior to sensory pore, and these ventral setae and sensory pore all anterolateral to SSm; S9, S10 and SSm arranged almost in line. Postmentum weakly rugose anteriorly. Antenna 0.45–0.49 times as long as head capsule; lengths of first to fourth segments (in μm) 185–223 (196, n = 10), 70–80 (75, n = 10), 4–5 (4, n = 10) and 4–5 (4, n = 10); AR 2.2–2.5. First segment 7.4–8.2 times as long as its basal width, with ring organ positioned 0.64–0.72 from base; blade 75–85 (80, n = 5) μm long, reaching middle of segment 3; accessory blade 78–88 (82, n = 7) μm long. Second segment ( Fig. 38 ) 9.3–10.3 times as long as its basal width; style 7–10 (8, n = 6) μm long, reaching middle of segment 4; inner peg sensillum 5–6 (5, n = 11) μm long, fused with apical margin of segment 2; outer peg sensillum 4–5 (5, n = 11) μm long, normal. Third segment subequal to segment 4, and placed on membranous base. Mandible ( Fig. 39 ) 78– 88 (82, n = 16) μm long, 0.29–0.30 times as long as antenna, with apical tooth 2.7–3.0 times as long as basal width. Basal segment of maxillary palp ( Fig. 40 ) 31–33 (32, n = 15) μm long, 3.0–3.4 times as long as wide, with ring organ positioned 0.62–0.69 from base. Ligula ( Fig. 41 ) 73–80 (76, n = 14) μm long, 2.0–2.3 times as long as its toothed width, with granulose area rounded and occupying its basal 0.21–0.28; median tooth 1.7–2.0 times as long as wide. Paraligula 30–35 (33, n = 14) μm long, with fork positioned 0.57–0.67 from base; outer spine 2.0–2.6 times as long as inner spine. Pecten hypopharyngis with row of 8–11 teeth.

Body. Procercus 3.8–4.4 times as long as wide with 7 anal setae; both lateral setae located respectively 0.33– 0.36 and 0.66–0.76 from base. Posterior parapod with 16 yellow claws serrated along inner and/or outer margin; one of smaller claws bifid with semicircular base ( Fig. 42 ).

Remarks. In the original description of Krenopelopia togavicea , the authors ( Sasa & Okazawa 1992b: 214) noted, “Costa ending much proximal to tip of M”. However, the feature does not match with that of Krenopelopia , of which costa ends above or slightly beyond M ( Murray & Fittkau 1989). Further they wrote, “Ground color of scutum yellow, median and lateral stripes brownish yellow”. We re-examined the holotype and it was proved that the male has inner midtibial spurs each with an elongated main tooth and four lateral teeth, abdominal tergite IX without setae, and very long phallapodemes in the hypopygium, and that the scutal vittae are indistinct because of the treatment with KOH solution, but dark markings are distinct on the lateral scutal vittae anteriorly and posteriorly, and the prescutellar area along the median line. Moreover, the re-examination has shown that the male abdomen is pale on tergites II and V. The species thus is valid as a member of Paramerina , characterized by the dark scutal markings and the male abdomen with anterior dark bands on the tergites III, IV, VI–VIII.

The pupa and the adult male will easily key to Paramerina in Fittkau & Murray (1986) and Murray & Fittkau (1989), respectively. The larva, however, will key past neither couplet 20 in Fittkau & Roback (1983), nor couplet 18 in Epler (2001), nor couplet 16’ in Ferrington et al. (2008) because of the second antennal segment having a normal outer peg sensillum and an inner peg sensillum fused with its apex. Epler (2001: 4.61) wrote concerning the North American Paramerina larvae, “Although Fittkau & Roback (1983) stated that the claws of the posterior parapods were simple, some species possess bifid small claws.” Also the larva of P. togavicea is armed with a bifid small claw on the posterior parapod. In addition, the larval maxillary palp has a single basal segment that is 3.0–3.4 times as long as wide and provided with a ring organ at 0.62–0.69 distance from the base.

The species much resembles P. d i v i s a, which was reported under the genus Pentaneura on the basis of males from Gotemba City, Shizuoka Prefecture, Japan, by Tokunaga (1937a). He wrote (p. 53), “Body 2.5 to 3.5 mm in length, yellowish white, with lateral vittae, but without median vittae on scutum. Abdomen yellowish white, first tergum with a pair of faint pale brown clouds; second without markings; third and fourth each with a broad brown cephalic band; fifth with a faint pale brown median cloud; the following three broadly or entirely brown.” However, the species is distinct from the European P. d i v i s a. The male somewhat differs from that of P. d i v i s a in the indistinct median scutal vittae (see Walker 1856, Goetghebuer 1936 and Fittkau 1962 for the latter species). Also the pupa is separable from that of P. d i v i s a. The thoracic horn is provided with an oval corona and a relatively large plastron plate, which is 0.42–0.53 times as long as the corona and 3.3–5.7 times as long as the width of its neck: while that of P. d i v i s a has a somewhat triangular corona and a smaller plastron plate ( Zavȓel & Thienemann 1921, fig. 7B; Fittkau 1962, fig. 274; Langton 1984, pl. 17a). The abdominal segment VII has four pairs of LS-setae in P. togavicea , but three pairs of LS-setae in P. d i v i s a ( Fittkau 1962, fig. 284b; Langton 1984, pl. 17a). Differences between the larvae of these species are more distinct. The larva of P. togavicea has a uni-colored head capsule, and posterior parapods each with a bifid small claw. In contrast, that of P. d iv i s a has a bi-colored head capsule ( Rieradevall & Brooks 2001), and posterior parapods without bifid claws ( Laville 1971). Furthermore, the larva of P. t o g a v - icea has a maxillary palp with a single basal segment, and second antennal segment fused with the inner peg sensillum at the apex, which are unique features among the known larvae of this genus.

We re-examined also the voucher specimens, deposited in NSMT, reported under the name of Paramerina divisa by Sasa & Hasegawa (1988). Morphological features of the adult and the pupa fit those of P. togavicea .

In the report of Pentaneura divisa, Tokunaga (1937a: 53) wrote, “In a small male specimen from the same locality, the pale brown clouds of the first and fifth terga disappear, being entirely yellow, and the penultimate segment of the antenna is abnormally short, the antennal ratio being only 0.83.” The small specimen may be P. o k i - genga, although we have not examined the small specimen as well as the large one. These specimens are still extant in the Kyushu University Museum, but their conditions are too poor to make necessary observations because of the long-term alcoholic storage (Tadauchi, pers. comm.). Actually, the larvae of P. okigenga and P. t o g a v i c e a are frequently found in the same locality.

Figures

FIGURES 29 – 32. Paramerina togavicea (Sasa et Okazawa), male (29 – 31) and female (32). 29, Thorax, showing marking pattern, dorsal view; 30, wing; 31, hypopygium, dorsal view; 32, genitalia, ventral view.

FIGURES 33 – 42. Paramerina togavicea (Sasa et Okazawa), pupa (33 – 36) and larva (37 – 42). 33, Thoracic horn with basal lobe; 34, abdominal segments VII – IX, dorsal view, left lateral setae omitted; 35, shagreen on posteromedial part of abdominal sternite II; 36, shagreen on posteromedial part of abdominal tergite IV; 37, head with chaetotaxy, dorsal view (R) and ventral view (L); 38, apex of antenna; 39, mandible, seta subdentalis and ventrolateral setae omitted; 40, maxillary palp with apical stylets; 41, ligula and paraligula; 42, smaller claws of posterior parapod. Abbreviations as in Figures 19 – 28.