Phytoliriomyza igniculus Kato, 2022

Kato, Makoto, Yamamori, Luna & Imada, Yume, 2022, Diversity underfoot of agromyzids (Agromyzidae, Diptera) mining thalli of liverworts and hornworts, ZooKeys 1133, pp. 1-164 : 1

2. Phytoliriomyza igniculus Kato sp. nov.

Figs 3 , 4

Material examined.

Holotype: Japan: 1♂ (MK-AG-a323), Matsubara-ko, Koumi, Nagano Pref. (36.053896°N, 138.461847°E, 1110 m), 18-IV-2021 (as larva), emerged on 17-V-2021, NSMT-I-Dip 31890. Paratypes: Japan: 1♂1♀ (MK-AG-a454, a453), same data as holotype, emerged on 17-V-2021, NSMT-I-Dip 31891, 31892; 1♀ (MK-AG-a324), Iwaobetsu, Shari, Hokkaido, 1-V-2021 (as larva), emerged on 28-V-2021, NSMT-I-Dip 31893; 1♀ (MK-AG-a325), Odarumi, Makioka, Yamanashi Pref., 30-VI-2021 (as larva), emerged on 4-VII-2021, NSMT-I-Dip 31894; 1♀ (MK-AG-a326), Ikawa-toge, Aoi-ku, Shisuoka Pref., 26-V-2021 (as larva), emerged on 9-VI-2021, NSMT-I-Dip 31895; 1♀ (MK-AG-a28), Shirabiso-toge, Kamimura, Iida, Nagano Pref., 27-IV-2014 (as larva), emerged on 22-V-2014, NSMT-I-Dip 31896.

Other material.

Japan: 35♂37♀, same data as holotype, emerged on 8-17-V-2021; 9♂5♀, Iwaobetsu, Shari, Hokkaido, 1-V-2021 (as larva), emerged on 26-28-V-2021; 3♂1♀, Horoman-kyo, Samani, Hokkaido, 30-IV-2021 (as larva), emerged on 26-31-V-2021; 1♂2♀, Odarumi, Makioka, Yamanashi Pref., 27-VI-2014 (as larva), emerged on 15-VII-2021; 1♂1♀, Shirabiso-toge, Kamimura, Iida, Nagano Pref., 27-IV-2021 (as larva), emerged on 23-25-V-2021; 22♂20♀, Ikawa-toge, Aoi-ku, Shisuoka Pref., 26-V-2021 (as larva), emerged on 8-17-VI-2021.

Diagnosis.

A large yellow species (wing length 2.0-2.1 mm) having a pruinose dark gray scutum with a trapezoid yellow patch medially on posterior 1/3, a yellow scutellum, black 1st flagellomeres, yellow maxillary palpi, yellow halteres, and yellow legs. Male epandrium with a comb comprising five or six fused long tubercle-like setae. Larva mines the thallus of Marchantia polymorpha .

Description.

Adult male (Fig. 3A-E ).

Head: Head light yellow, with ocellar tubercle dark brown, frons yellowish brown, back of head dark brown excluding margins (Fig. 3C ). Antenna porrect, first flagellomere black, pedicel and scape yellow. Arista subbasal, black, pubescent. Clypeus, face, gena, parafacial and postgena yellow. Proboscis normal, yellow; palpus yellow, cylindrical. Chaetotaxy: Front orbitals three pairs; one ori directed inward; two ors directed upward (Fig. 3B ). Orbital setulae minute and erect, in a single row.

Thorax: Thorax pruinose. Scutum dark gray with a trapezoid pale yellow patch medially on posterior 1/3 (Fig. 3D ). Scutellum pale yellow. Subscutellum with anterior half yellow, ventral half brown. Mediotergite brown, anatergite and katatergite yellow (Fig. 3B ). Pleuron yellow; propleuron with small brownish spots on venter; anepisternum with three brown spots on anterior and middle dorsal margins and middle venter; several small brown spots on anepimeron, katepisternum and meron with brow patches on venter (Fig. 3B ). Haltere yellow. Calypter margin and hairs gray (Fig. 3B ). Leg segments yellow; tibia and tarsus darker (Fig. 3A ). Chaetotaxy: Scutum with 1+3 dorsocentrals, shortened anteriorly (Fig. 3D ). Acrostichal setulae six or seven pairs in two rows. Wing: Wing length 2.1 mm, costa reaching M1 (Fig. 3A ). Length of ultimate section of vein M4 divided by penultimate section 1.3-1.7.

Abdomen: Abdomen dorsally subshiny yellow, with a pair of brown lateral semicircular patches on anterior half of the 2nd tergite; epandrium dark brown (Fig. 3E ). Genitalia: (Fig. 3F-I ). Epandrium rounded apically, with a long tubercle-like seta on subposterior inner-lateral surface; inner-anterior surface with a comb comprising five or six fused long tubercle-like setae (Fig. 3I ). Surstylus hood-like, curved inward, setose apically, with single long tubercle-like seta on outer distal margin. Cercus narrow, setose, with a strong seta apically (Fig. 3I ). Subepandrial sclerite with one pair of flat, pale, blade-like ventral process and one pair of setae outward (Fig. 3I ). Hypandrium slightly sclerotized along outer margin (Fig. 3F ). Postgonite bare and broadly rounded apically (Fig. 3H ). Phallophorus with deep incision below, articulated with phallapodeme, fused to epiphallus (Fig. 3F, G ). Basiphallus with a narrow plate on left side; length similar to that of mesophallus (Fig. 3G ). Hypophallus broad, membranous, medially with a pair of fused linear sclerites; distal half diverging (Fig. 3G ). Paraphallus absent. Mesophallus dark, cylindrical, widest subbasally, slightly shorter than distiphallus (Fig. 3G ). Distiphallus comprising one pair of stout tubules; basal half composed of ventral dark bulbous sclerite and weaker medial region curving outward; distal half cylindrical and well-pigmented, with truncated, unpigmented apex (Fig. 3G ). Ejaculatory apodeme fan-shaped, blade pale with clear margin, with narrow stalk, broad base, and clear sperm pump.

Female. Similar to male, but slightly larger and frons wider. Wing length 2.1 mm. Postabdomen: (Fig. 3K, L ) Oviscape dark brown, setigerous. Tergite 10 cruciform, laterally uniting narrow pleural sclerites (Fig. 3K ). Each cercus with two stout, apical, trichoid sensilla, 1/3 length (Fig. 3L ). Spermathecae orbicular (Fig. 3K ).

Etymology.

The specific name (igniculus = small fire) refers to the yellow oblong patch on the scutum.

Japanese name.

Kitsunebi-zenigoke-hamoguribae.

Host plant.

Marchantia polymorpha ( Marchantiaceae ).

Mine.

Larvae construct linear-botch mines in the thallus, particularly in the midrib, and pupate in the mines (Fig. 4C-E ).

Biological notes.

The host plants from which this species emerged, grow on mesic soils along roads in cool temperate forests (beech forests dominated by Fagus crenata in Honshu and deciduous oak forests dominated by Quercus crispula in Hokkaido) and on levees of paddy fields in a cool temperate forest ecosystem (Fig. 4A, B ). Our rearing records suggest that this species is univoltine, and that adults emerge from overwintered pupae in spring.

Distribution.

Japan: Hokkaido and Honshu (Fig. 2 ).

Remarks.

This species is distinguished from all other species of Phytoliriomyza with black-banded yellow thorax by the unique brown patches on the 2nd abdominal tergite (absent in other species). This species resembles P. izayoi , P. chichibuensis and P. caliginosa in the yellow pattern of the scutum and scutellum; it is distinguished from them by the wholly yellow scutellum without dark lateral corners and by the number of tubercle-like setae of the comb on the male epandrium ( P. igniculus , 5-6; P. izayoi , 6-8; P. caliginosa , 8-11). This species also resembles P. cometiformis and P. luna in having a yellow scutellum; it is distinguished from them by the number of tubercle-like setae of the comb on the male epandrium ( P. igniculus , 5-6; P. cometiformis , 3; P. luna , 7-8). This species also resembles P. islandica in the yellow pattern of the scutellum; it is distinguished by the black first flagellomere (brown in P. islandica ).

Figures

Figure 2. Locality records of three Phytoliriomyza species associated with Marchantia spp.: P. dorsata, P. igniculus, P. tsukuyomi, P. marchantiae and P. nubatama.

Figure 3. Phytoliriomyza igniculus sp. nov. A-E holotype male A habitus B lateral body C frontal head and ventral body D dorsal thorax E thorax in posterior view F-H male genitalia F whole genitalia G phallic complex H postgonite I epandrium J a living female fly on a thallus of Marchantia polymorpha K, L female postabdomen K oviscape and spermatheca L tergite 10.

Figure 4. Habitat of Phytoliriomyza igniculus sp. nov. and its host plant, Marchantia polymorpha A habitat at levee of a rice field at type locality B thalli with male receptacles C mined thallus containing an internal puparium (arrow) D the same thallus in transmitted light (arrows indicating mines) E mined thallus at Ikawa-toge.