Prosimulium kiotoense Shiraki, 1935

Kim, Sam-Kyu, 2020, Two new genera of black flies (Diptera: Simuliidae) of Korea, Journal of Species Research 9 (1), pp. 11-18 : 13-15

Prosimulium kiotoense Shiraki, 1935 ( Figs. 1 , 2 )

Prosimulium kiotoense Shiraki, 1935: 6 . Type locality: Kyoto, Japan.

Prosimulium kiotoense: Saito & Kajihara, 1975 (Japanese record); Saito et al., 1983 (Japanese record); Baba & Takaoka, 1985 (Japanese record and ecology); Baba & Takaoka, 1988 (ecology); Saito et al., 1988 (Japanese record); Baba & Takaoka, 1991a (ecology); Baba & Takaoka, 1991b (ecology); Baba & Takaoka, 1992 (ecology); Saito, 2015 (Japanese list and name); Adler, 2019 (world checklist).

Prosimulium (Prosimulium) kiotoense: Uemoto et al., 1973 (revision); Matsuo & Uemoto, 1975 (ultrastucture); Saito & Sato, 1984 (Japanese record); Saito et al., 1985 (Japanese record); Saito et al., 1990 (Japanese record); Saito et al., 1993 (Japanese record); Saito et al., 1996a (Japanese record); Saito et al., 1996b (Japanese record); Saito & Kanayama, 2002 (Japanese record); Uemoto, 2005 (Japanese key and illustrations).

Prosimulium hirtipes , not Fries: Ogata & Sasa, 1954 (Japanese list); Bentinck, 1955 (key and illustrations); Ogata & Sasa, 1955 (Japanese key and illustration); Shogaki, 1956 (Japanese list); Ogata & Fukui, 1957 (ecology).

Diagnosis. Prosimulium kiotoense can be easily distinguished from other Korean black flies by the following characteristics: cocoon amorphous, entirely cover the pupa; gill of 16 filaments; larval antenna with proximal and medial article pale, distal article brown; labral fan with 32 rays; hypostoma with median tooth prominent, trifid; postgenal cleft shallow, apex straight.

Description. Pupa. Body length 2.7-3 mm (n = 7). Pupa ( Fig. 1A, 1B ) brown to light brown ground color. Gill ( Fig. 1B, 1E ) with 16 filaments in 3 main stems; uppermost stem with 3 stalks, give rise to 8 filaments arranged in 2 + (1 + 2) + (1 + 2); middle and lowermost stems each with 2 stalks, give rise to 8 filaments in (2 + 2) arrangement, 0.6 × as long as pupal body length. Head ( Fig. 1C, 1D ) with cephalic apotome light brown, densely covered with small tubercles; frontal trichome 3 pairs, simple; facial trichome 1 pair, simple. Thorax ( Fig. 1B, 1D ) brown, densely covered with small tubercles; thoracic trichome 5-6 pairs, long, simple. Abdomen ( Fig. 1F, 1G ) densely covered with small tubercles; abdominal tergite II with 4 pairs of subapical setae; tergites III and VI apically with 4 pairs of anterior directed hooks; tergites V- IX anteriorly with distinct spine combs; tergites VI- VIII with spin at posterolateral margin of each tergites; tergite VIII with 3 pairs of long golden setae. Abdominal sternum ( Fig. 1G ) with sternite IV with 2 pairs of small hooks; sternite Vwith 2 pairs of large hooks; sternites VI and VII with 1 pair of hook. Terminal spine ( Fig. 1G ) well developed, long, directed anteriorly. Cocoon ( Fig. 1A ) amorphous, loosely woven, entirely cover the pupa and base of gill filaments.

Larva (penultimate instar). Body length 5.3 mm (n = 1). Body ( Fig. 2A ) brownish grey ground color. Head capsule ( Fig. 1B ) brown to light brown. Head spots ( Fig. 2B ) with anteromedial spots distinct, other spots indistinct. Labral fan ( Fig. 2C ) with 32 primary rays. Antenna ( Fig. 2D ) with proximal and medial article transparent, distal article brown, as long as labral fan stem, gradually tapered toward apex; proportional ratio from proximal to distal article as 0.8: 1: 1.2. Postgenal cleft ( Fig. 2E ) shallow, apex straight or quadrate, laterally with elongate lateral spot. Hypostoma ( Fig. 2F ) with 7 teeth, apically pointed; median tooth prominent, trifid, lateral teeth longer and larger than sublateral teeth, intermediate teeth well developed. Hypostomal seta 3 pairs, simple. Subesophageal ganglion ( Fig. 2E ) not pigmented. Prothoracic proleg ( Fig. 2G ) with well developed lateral sclerite, vertical portion well developed. Rectal papillae with 3 simple lobes. Posterior proleg ( Fig. 2H ) with 10- 13 hooks in 68 rows. Anal sclerite Xshaped with anterodorsal arms clearly longer than the posteroventral arms.

Specimens examined. Korea: Gyeonggi-do, Gapyeong-gun, Buk-myeon, Jeokmok-ri, Gapyeongcheon stream, 37°57 ʹ 48 ʺ N, 127°26 ʹ 58 ʺ E, altitude 290 m. 10.v.2019, SK Kim (1 pupa); ditto, 22.v.2019, SK Kim (2 pupae); Gyeonggi-do, Gapyeong-gun, Buk-myeon, Dodae-ri, Myeongjicheon stream, 37°56 ʹ 07 ʺ N, 127°29 ʹ 18 ʺ E, altitude 210 m, 10.v.2019, SK Kim (4 pupae, 1 penultimate instar larva) .

Distribution. Korea (Gyeonggi-do, new record), Japan (Honshu, Kyushu).

Stream information. Two streams, the only localities where larvae and pupae of P. kiotoense were collected so far, are separated by Mt. Myeongjisan (1,267 m) by a distance of 4.6 km. Both were medium to large-sized streams with moderate to rapid flow and totally exposed to the sun. Stream beds consisted of boulders and rubble. Edges of the streams were lined with trailing vegetations including reeds. The streams were 10-20 m wide and 15-20 cm deep, but the streams were partially dried up due to spring drought.

Remarks. Japanese species assigned to magnum species-groups have 22-48 gill filaments in pupa, while species in hirtipes species-group, which P. kiotoense belongs to, have 16 gill filaments in pupa. Morphologically similar species, P. jezonium (Matsumura, 1931) and P. kanii Uemoto, Onichi & Orii, 1973 , can be distinguished from P. kiotoense by the shape of gill filaments and diverging condition between dorsal and ventral stem of gill filaments ( Uemoto et al., 1973). General description of P. kiotoense larva and pupa from Korea fits well with that of Uemoto et al. (1973). However, a great difference exists in pupal and larval size between Japanese ( Uemoto et al., 1973) and Korean specimens: pupal body length 5.7- 6.8 ( Japan) vs. 2.7-3 ( Korea) / larval body length 6.8- 8.1 ( Japan) vs. 5.3 ( Korea). For larval body size, however, the studied material might be insufficient since only single penultimate instar larva was available for Korea. Although P. kiotoense is known as a univoltine and widespread in Japan ( Uemoto et al., 1973; Baba & Takaoka, 1988), they were found only from two streams within the same district (Gyeonggi-do, Gapyeong-gun) in Korea. Since the immature stages are coldwater life forms, larval period is from autumn to early spring and has seven larval instars ( Uemoto et al., 1973). First instar larvae were appeared on November and 7 th instar larvae were first appeared early April ( Baba & Takaoka, 1991a). It is believed that P. kiotoense can attack cattle and occasionally humans ( Uemoto et al., 1973). All larvae and pupae were collected only twice in May 2019 from two streams, and Ifailed to collect P. kiotoense in subsequent attempts in other months at the same streams. This species was collected along with Simulium (Boreosimulium) konoi , Simulium (Nevermannia) uchidai , Simulium (Simulium) suzukii , Simulium (Simulium) yamatoense , and Simulium (Simulium) japonicum .

Figures

Fig. 1. Pupa of Prosimulium kiotoense Shiraki. (A) Pupa with cocoon, lateral view; (B) Pupa (cocoon removed), dorsolateral view; (C) Head, anterolateral view; (D) Head and thorax, dorsal view; (E) Gill filament, lateral view; (F) Abdomen, dorsal view; (G) Abdomen, later- al view. Scale bars, 1 mm (A, B); 100 μm (C); 500 μm (D-G).

Fig. 2. Larva of Prosimulium kiotoense Shiraki. (A) Larva, lateral and dorsal view; (B) Head, dorsal view; (C) Labral fan (detached from the head); (D) Head, dorsolateral view; (E) Head, ventral view; (F) Hypostoma, phase contrast photomicrograph; (G) Prothoracic proleg, lateral view; (H) Posterior circlet, phase contrast photomicrograph. Scale bars, 1 mm(A); 200 μm (B-E, G); 100μm (H); 50μm (F).