Ascid mites are important predators in many soil ecosystems (Walter, 1988; Kinnear, 1991) with organic soil, grasses, mosses, or dead organic matter on the soil surface and barks. Also these are often found from of forests, crop land and other habitats associated with humans and other animals (Lindquist and Evans, 1965; McMurtry et al., 2013, 2015).
The genus Asca of the family Ascidae are an ecologically diverse group and easily recognized by the presence of a pair of tubercles projecting from the posterolateral corners of the posterior dorsal shield (Hurlbutt, 1963). The most diverse genus was Asca, the first numerous in the Oriental and Neotropical regions, and the second in the Nearctic region (Santos et al., 2018). This genus Asca was reported first as Acarus aphidioides (= Asca aphidioides) by Linnaeus (1758). They are predatory, feeding on other mites, insects, collembolans or nematodes (Hurlbutt, 1963; Walter et al., 1993).
Species diversity of Ascidae encompasses 17 genera, 372 species in the world (Moraes et al., 2016) and 10 genera 24 species in Korea (NIBR, 2013, Table 1). Among Ascide, the genus Asca have been reported 148 species in the world (Moraes et al., 2016; Santos et al., 2018). However, until now, six species of the genus Asca have been reported in Korea: Asca aphidioides (Lee et al., 1996; Kaczmarek, 2000; Jung et al., 2010; Keum et al., 2010), A. garmani (Lee et al., 1996; Jung et al., 2010), A. kosungensis (Lee et al., 1997; Lee, 2009), A. nubes (Lee, 1995; Lee, 2009), A. odowdi (Lee et al., 1997; Lee, 2009) and A. sculptrata (Lee et al., 1996; Jung et al., 2010). From the moss samples collected near Muljangori craer lake 936 m alt. which is located on the eastern slope of Hallasan Mountain in Jeju, we firstly discovered unrecorded one species, Asca bicornis Canestrini & Fanzago, 1877. So, in this study, we report this as a new record to Korean Mesostigmata fauna by providing the morphological illustration and description. In addition, we provide identification key about the genus Asca distributed in Korea.
Materials and Methods
We collected soil and other organic materials from Muljangori-oreum (E126°31′, N33°22′, alt. 936 m) in Jeju, Korea. Muljangori-oreum is one of 370 parasitic cones of Hallasan volcanic mountain, with crater lake on top. Mite specimens were extracted using Berlese-Tullgren funnels (30 W, 72 h) from soil samples and preserved in 70% ethyl alcohol. Mites were mounted on slide glass in polyvinyl alcohol (PVA) mounting medium (Downs, 1943) and further identified. The line drawings and examination of the specimens were performed with an Olympus BX50 phase contrast microscope equipped with a drawing tube and traced over using Adobe Illustrator CS 2014® program. New record species are deposited in Insect Ecology Lab, Department of Plant Medicine, Andong National University (ANU), Andong, Korea.
Taxonomic accounts
Family Ascidae Oudemans, 1905
Genus Asca von Heyden
Asca von Heyden, 1826: 610.
Type species: Gamasus aphidioides, Fab. (sic), 1805 (= Acarus aphidioidesLinnaeus, 1758: 616), by original designation.
CeratozerconBerlese, 1910: 246 (Synonymy by Vitzthum, 1929: 30; Ryke, 1962: 157; Hurlbutt, 1963: 481; Farrier & Hennessey, 1993: 26; Halliday et al., 1998: 17).
Ceratozercon. - Berlese, 1913: 204; 1918: 188.
Asca. - Vitzthum, 1929: 30; Oudemans, 1936: 366; Hirschmann, 1959: 4; Ryke, 1961: 127; 1962: 158; Karg, 1962: 36; 1965: 203; 1971: 253; Bernhard, 1963: 19; Evans, 1963: 286; Hurlbutt, 1963: 481; Lindquist & Evans, 1965: 42; Athias-Henriot, 1968: 243; 1969: 126; Genis et al., 1969: 86; Evans & Till, 1979: 198; Farrier & Hennessey, 1993: 26; Walter et al., 1993: 1330; Halliday et al., 1998: 17; De Leon-Facundo & Corpuz-Raros, 2004: 202; Kalúz & Fend’a, 2005: 42; Gwiazdowicz, 2007: 58; Beard et al., 2011: 8.
Asca (Ascoseius) Karg, 1979: 257.
Diagnosis. Dorsal shield divided into podosomal and opisthosomal shield, both usually ornamented (smooth or with slight ornamentation in few species), without transverse and nearly straight lines or delineated strip along lateral margins. Anterior end of podosomal shield not strongly deflexed; podosomal shield usually with 17 pairs of setae (rarely with 16, 18 or 19; always without z1). With pair of posterior projections (horns) on opisthosomal shield usually bearing setae Z4 and S5. Three pairs of sternal setae on the sternal shield and fourth pair free. Genital shield not wide enough to include iv5, but including st5; posteriorly truncate. Opisthogaster with eight pairs of setae in addition to circumanal setae. Peritreme extending from stigma to region between j1 and j2, narrower than diameter of stigma. Peritrematic shield wide usually fused with dorsal shield between level of s1 - r2; posteriorly truncate and broadly fused with exopodal shield beside coxa IV.
Asca bicornis Canestrini & Fanzago, 1877 쌍털뿔응애(신칭)
Gamasus (Sejus) bicornis Canestrini & Fanzago, 1877: 103.
Laelaps bicornis. - G. Canestrini & R. Canestrini, 1882: 78. Sejus bicornis. - Canestrini, 1885: 91.
Ceratozercon bicornis. - Berlese, 1913: 204; Halbert, 1923: 375. Asca bicornis. - Buitendijk, 1945: 309; Willmann, 1949: 112; Evans, 1958: 584; Halaskova, 1959: 17; Ryke, 1961: 129; Schweizer, 1961: 137; Bernhard, 1963: 72; Hurlbutt, 1963: 495; Karg, 1965: 221; 1971: 274; 1993: 283; Pinchuk, 1976: 54; Kalúz & Fend’a, 2005: 122; Gwiazdowicz, 2007: 61; Çakmak et al., 2011: 581; Kontschan & Ujvari, 2013: 79.
Asca (Asca) bicornis. - Karg, 1979: 258.
Asca novaWillmann, 1939: 246 (Synonymy by Willmann, 1949: 112; Evans, 1958: 584; Karg, 1993: 283).
Asca nova. - Womersley, 1956: 511; Ryke, 1961: 132; Hurlbutt, 1963: 495; Dziuba, 1972: 165.
Asca (Asca) nova. - Karg, 1979: 258; Farrier & Hennessey, 1993: 28.
Specimens examined: 31 females, Muljangori-oreum, Hallasan national park, Jeju island, Republic of Korea, N33°22′, E126°31′, alt. 936 m, 22 April 2017, C. Jung coll., from moss habitat.
Diagnosis. Epistomes with a triramous apex. Peritremes long, reaching coxae I, peritremal shield broad (Fig. 1). Lateral caudal projection of with pair of posterior projections (horns) on opisthosomal shield usually bearing setae Z4 and S5. All dorsal setae nude, needle shaped j1 and other frontal setae shorter, caudal part of body with longer setae. Proximal part of sternal shield 167 μm long and 193 μm wide, with reticulate pattern in front-lateral sides, wearing 17 pairs of setae. Opisthosomal part of dorsal shield 157 μm long and 201 μm wide, with fine and big scale-like pattern in medio-proximal part, shield wearing 16 pairs of nude setae, Z5 = 54 μm, J1 = 15 μm, J3 = 31 μm long. Sternal shield without structure, shield with expressive proximal corners, presternal sclerites confluence with sternal shield. Metasternal shield on soft cuticle or on genital shield, St1 - 3 on sternal shield Tritosternum with trapezoidal base and sparsely pilose laciniae. Genital shield caudally broad-ended, with straight caudal margin, pair of genital setae on lateral margins. Sternal and genital shields smooth. Two pairs of narrow, oblonged postgenital sclerites and two pairs of short needle-shaped setae between genital and ventrianal shields. Ventrianal shield big, proximally slightly concaved and caudally rounded, with cross-running parallel pattern in proximal part. Shield wearing 7 pairs of nude setae, two caudal pairs (Jv4, 5) longer. Leg setae short blunt.
Distribution. USSR, Western Europe (Bregetova, 1977), Germany (Karg, 1979), Slovakia (Kaluz and Fenda, 2005), Poland (Gwiazdowicz, 2007), Hungary (Kontschán and Ujvari, 2013) and is now recorded in Korea (Fig. 2).
Remarks.Asca bicornis was found from diverse habitats from dry to wet soils and even from mosses. Specimens for this report were from moss and humus in soi near the crater lake of Muljangori-oreum, Hallasan national park, Jeju Island in Korea. This is the first record of this species in the Eastern Asia.
Notes.Asca aphidioides is a cosmopolitan species with a single conspicuous pinnate seta on each posterior horn, but Asca bicornis is elongate posterior horns, each bearing two nude setae.
Key of the genus Asca to species distributed in Korea.
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Postero-latral horns each with 1 conspicuous seta; small, tooth-like ornamentation (microtubules) on posterior dorsal shield (aphidioides species-group). ·································· 2 - Postero-lateral horns with 2 conspicuous, subequal setae; posterior microtubules absent. ·········································· 3
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Majority of dorsal setae strongly hairy (R2 and J5 nude only), lateral caudal projection of Z4 wearing one hairy seta. ···································· Asca aphidioides (Linnaeus, 1758) - Dorsal shield setae pilose, S5 with long, fine pilosity; setae z5, z6 similar in size to adjacent setae; a row of microtubules lateral seta J4. ························· Asca garmaniHurlbutt 1963 - Cylindrical tubercle-like projection of posterior corner bears only one pinnate seta S5; seta Z4 minute. Setae r4 to r7 strongly pilose, while setae R1 slightly pilose and remainder is simple. ·································· Asca nubes Ishikawa, 1969 - Anterior dorsal shield having 17 pairs of simple setae; a pair of round sculptures found between the tubercles anterior to J5. ············································ Asca sculptrataAoki, 1968 - Posterior dorsal shield with 17 pairs of setae, most of simple, but those on posterior idiosoma more barbed in posterior ones. J3 and J4 with or without minute barbs, Z3 and S4 with distinct barbs. Setae on tubercle as long as J5 and pinnate. ······················································· Asca odowdiLee, 1997 - Posterior dorsal shield with 15 pairs of setae. J3 reaches the base of J4. Two pairs of setae on postero-lateral tubercles as long as J5 and pinnate. ············ Asca kosungensisLee, 1997
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Setae J5 small to minute; dorsal shield setae tapering, finely to densely pilose or smooth (bicornis species-group). - All dorsal setae nude and needle shaped, lateral caudal projection of Z4 wearing two nude setae. ···························· ························· Asca bicornis Canestrini & Fanzago, 1877