Phytoliriomyza plagiochasmatos 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

9. Phytoliriomyza plagiochasmatos Kato sp. nov.

Fig. 17

Material examined.

Holotype: Japan: 1♂ (MK-AG-a526), Narahara, Ueno, Tano, Gunnma Pref. (36.089°N, 138.689°E, 990 m asl), 18-IV-2021 (as larva), emerged on 15-V-2021, NSMT-I-Dip 31940. Paratypes: Japan: 1♂1♀ (MK-AG-a524, a523), same data as holotype, emerged on 19-25-V-2021, NSMT-I-Dip 31941, 31942.

Other material.

Japan: 1♂3♀, same data as holotype, emerged on 19-25-V-2021; 3♀, Ozasu, Ogano, Chichibu, Saitama Pref., 28-XI-2014 (as larva on Asterella cruciata ), emerged on 24-27-IV-2015.

Diagnosis.

A small species (wing length 1.4-1.5 mm) having subshiny brown scutum with an oval yellow pattern extending from mid-posterior margin to scutellum, yellow 1st flagellomere, yellow maxillary palpus, yellow halteres, and yellow legs. Male epandrium with an imperfect comb comprising two short tubercle-setae. Larva mines the thallus of Plagiochasma pterospermum and Asterella cruciata .

Description.

Adult male (Fig. 17A-E ).

Head: Head light yellow, with ocellar tubercle brown, back of head dark brown (Fig. 17C ). Antenna porrect, first flagellomere, pedicel and scape brown. Arista subbasal, black pubescent. Clypeus, face, gena, parafacial and postgena yellow. Proboscis normal, yellow; palpus yellow, cylindrical (Fig. 17C ). Chaetotaxy: Front orbitals three pairs; one ori directed inward; two ors directed upward (Fig. 17B ). Orbital setulae minute and erect, in a single row.

Thorax: Thorax subshiny. Scutum subshiny yellow, with a brown medial stripe on anterior 2/3, one pair of brown presutural patches, and a pair of wide postsutural brown bands (Fig. 17B ). Mediotergite brown, and anatergite and katatergite yellow. Pleuron largely yellow, anepisternum and anepimeron with small brown patches, venters of katepisternum and meron brown (Fig. 17B ). Haltere yellow. Calypter margin and hairs gray. Leg segments yellow; tibia and tarsus darker (Fig. 17B ). Chaetotaxy: Scutum with 1+3 dorsocentrals, shortened anteriorly (Fig. 17D ). Acrostichal setulae six pairs in two rows. Wing: Wing length 1.5 mm, costa reaching M1 (Fig. 17A ). Length of ultimate section of vein M4 divided by penultimate section 1.7.

Abdomen: Abdomen dorsally subshiny grayish yellow (Fig. 17E ). Genitalia: (Fig. 17I-K ) Epandrium dark brown, rounded apically; inner-subdistal margin with a short, sharp-pointed tubercle-like seta; inner-anterior margin with an imperfect comb comprising two fused short tubercle-like setae; inner-lateral surface with a long tubercle-like seta. Surstylus extruded ventrally, setose apically (Fig. 17I, J ). Cercus narrow, setose. Subepandrial sclerite comprising two pairs of developed plate-like arms; ventral arm with a strong seta directed ventrally and pointed tip; dorsal arm ventrally pointed and with a spine directed outward (Fig. 17I ). Hypandrium slightly sclerotized along outer margin (Fig. 17G ). Postgonite bare, goose barnacle-shaped (Fig. 17H ). Phallophorus with deep incision below (Fig. 17G ), articulated with phallapodeme, fused to epiphallus (Fig. 17H ). Basiphallus as long as mesophallus, sclerotized basally and narrowly on right side, bifurcating apically (Fig. 17H ). Hypophallus broad, membranous and bilobed, with serrated margins; medially with a pair of dark fused sclerites (Fig. 17G, H ). Paraphalli dark, plate-like, diverging from base of mesophallus, outer margins sclerotized (Fig. 17G, H ). Mesophallus dark, cylindrical, widest subbasally, 3/5 as long as distiphallus (Fig. 17H ). Distiphallus comprising one pair of stout tubules; basal half composed of lateral lanceolate dark sclerites and short weaker region; distal half cylindrical, dorsally and laterally pigmented, with truncated, unpigmented apex (Fig. 17H ). Ejaculatory apodeme pale and fan-shaped with broad stalk; base wide to one side; sperm pump clear (Fig. 17K ).

Female (Fig. 17F ). Similar to male, but slightly larger. Wing length 1.4 mm. Postabdomen: (Fig. 17L, M ) Oviscape dark brown, setigerous. Tergite 10 trifurcate, laterally uniting narrow pleural sclerites. Each cercus with two stout, apical, trichoid sensilla, 2/3 length of cercus. Spermathecae semi-orbicular, with truncate proximal ends.

Etymology.

The specific name refers to the host plant genus Plagiochasma .

Japanese name.

Tsukikage-tsubozenigoke-hamoguribae.

Host plant.

Plagiochasma pterospermum ( Aytoniaceae ) and Asterella cruciata ( Asterellaceae ).

Mine.

Larvae construct linear-blotch mines in the thallus and pupate in the mines (Fig. 17Q ).

Biological notes.

The habitats of this species are outcrops of lime stones in temperate deciduous forests, where the host liverworts grow (Fig. 17O, P ), and this species was sympatric with P. arcus in some localities. Our rearing records suggest that this species is univoltine, and that adults emerge from overwintered pupae in spring.

Distribution.

Japan: Honshu (Fig. 16 ). Recorded only from limestone areas in Kanto districts.

Remarks.

This species resembles P. arcus , P. falcata and P. aratriformis in having a pair of brown lateral bands and a pale yellow mark on the scutum; it is distinguished from P. arcus by the yellow halteres (dark in P. arcus ), and from the last three species by the absence of seta on the surstylus of the male epandrium (surstylus apically setose in P. falcata and P. aratriformis ).

Figures

Figure 16. Locality records of three Phytoliriomyza species associated with Plagiochasma spp.: P. arcus, P. plagiochasmatos and P. calcicola.

Figure 17. Phytoliriomyza plagiochasmatos sp. nov. A-E holotype male A habitus B lateral C frontal D dorsal E posterior F paratype female (MK-AG-a 523), dorsal G-J male genitalia G whole genitalia, ventral H phallic complex, lateral I, J epandrium, ventral and anterior K ejaculatory apodeme, lateral L live male fly.