Phytoliriomyza dorsata Siebke, 1864

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

1. Phytoliriomyza dorsata Siebke, 1864

Fig. 1

Agromyza dorsata Siebke, 1864: 169.

Liriomyza reverberata . Frick 1952: 375; 1959: 409.

Lemurimyza dorsata . Spencer 1965: 28, 1969: 194.

Phytoliriomyza dorsata . Spencer 1976: 294; Spencer and Steyskal 1986: 303; Papp and Černý 2017: 317; Lonsdale 2021: 398; Černý et al. 2020: 214.

Material examined.

Japan: 1♂1♀ (MK-AG-a410, a26), Namari-kawa, Yakumo, Futami, Hokkaido (42.201151°N, 140.135658°E, 145 m asl), 10-VI-2012 (as larva), emerged on 13-17-VI-2012, NMNS.

Diagnosis.

A medium-sized yellow species (wing length 1.7-1.8 mm) that has a pruinose yellow scutum with one medial and two pairs of gray lateral stripes, black 1st flagellomeres, yellow maxillary palpi, yellow halteres, and yellow legs. Male epandrium inner-laterally with a comb consisting of six fused long tubercle-like setae, and surstylus with two tubercle-like setae. Larva mines the thallus of Marchantia polymorpha L.

Description.

Adult male (Fig. 1A-E ).

Head: Head light yellow, with ocellar tubercle brown, back of head dark brown (Fig. 1A ). Lunule distinct and slightly sunken. Antenna porrect, first flagellomere black, pedicel and scape yellow. Arista subbasal, black pubescent. Eye upright, bare. Face slightly convex. Gena straight. Clypeus, face, and postgena yellow. Proboscis normal, yellow; palpus yellow, cylindrical. Chaetotaxy: Front orbitals three pairs; one ori directed inward; two ors directed upward (Fig. 1B ). Orbital setulae minute and erect, in a single row.

Thorax: Thorax pruinose. Scutum yellow with medial dark stripe on anterior 2/3, with a pair of wide dark intra-alar stripes and a pair of narrower dark supra-alar stripes, adjoining a pair of lateral presutural dark ovoid spots (Fig. 1D ). Scutellum yellow with lateral corner brown. Subscutellum with anterior half yellow, ventral half brown. Mediotergite brown, anatergite and katatergite yellow. Pleuron largely yellow, venters of katepisternum and meron brown. Haltere yellow. Calypter margin and hairs gray. Leg segments yellow; tibiae and tarsi darker. Chaetotaxy: Scutum with 1+3 dorsocentrals, shortened in length anteriorly (Fig. 1D ). Acrostichal setulae eight or nine pairs in two rows. Wing: Wing length 1.7 mm, costa reaching M1 (Fig. 1A ). Length of ultimate section of vein M4 divided by penultimate section 1.7.

Abdomen: Abdomen dorsally subshiny yellow; epandrium dark brown (Fig. 1B ). Genitalia: (Fig. 1H-J ) Epandrium rounded apically, with a short tubercle-like seta on inner-middle surface, a comb comprising six long fused tubercle-like setae on inner-anterior surface, a few short tubercle-like setae immediately outward of the comb; and a row of minute tubercle-like setae on ventral inner margin (Fig. 1J ). Surstylus rounded, setose apically, with two short tubercle-like setae posteriorly. Cercus narrow, setose. Subepandrial sclerite with one pair of medial flat, plate-like ventral processes and hook-shaped protrusion directing anteriorly (Fig. 1J ). Hypandrium slightly sclerotized along outer margin (Fig. 1H ). Postgonite bare and broadly rounded apically (Fig. 1I ). Phallophorus with deep incision below, articulated with phallapodeme, fused to epiphallus (Fig. 1I ). Basiphallus with a narrow plate on left side (Fig. 1I ). Hypophallus membranous with a pair of small, parallel sclerites medially (Fig. 1I ). Paraphallus broad membranous, with pointed, lightly sclerotized margins; paraphalli diverging, angled anteroventrally, jointed basally (Fig. 1H ). Mesophallus dark, cylindrical, widest subbasally, length similar to that of distiphallus. Distiphallus comprising one pair of stout tubules; basal half composed of dorsal bulbous dark sclerites and weaker medial region; distal half cylindrical, dorsally and laterally pigmented (Fig. 1H ).

Female (Fig. 1F, G ). Similar to male, but slightly larger and frons wider. Wing length 1.8 mm. Postabdomen: (Fig. 1K, L ) Oviscape dark brown, setigerous (Fig. 1K ). Tergite 10 cruciform, laterally uniting narrow pleural sclerites (Fig. 1L ). Sternite bearing four pairs of marginal setae. Each cercus with two stout, apical, trichoid sensilla, 1/3 length of cercus (Fig. 1L ). Spermathecae orbicular (Fig. 1K ).

Japanese name.

Usuobi-zenigoke-hamoguribae.

Host plant.

Marchantia polymorpha ( Marchantiaceae ).

Mine.

(Fig. 1M-O ) Larvae construct linear mines in the thallus of liverwort in early instars, later entering the midrib, and pupating there, while mines are obscure from outside.

Biological notes.

The host plants from which this species emerged grow on wet cliffs along roads in a cool temperate forest of Quercus crispula .

Distribution.

Thus far, recorded from Europe, North America, and Japan. The authors recorded only from southern Hokkaido (Fig. 2 ).

Remarks.

The morphology of the Japanese specimens closely coincided with the description of P. dorsata by Spencer (1976), but not with the description by Papp and Černý (2017), particularly concerning the morphology of the epandrium and distiphallus, which suggests the presence of multiple related species in Europe. Related Phytoliriomyza species ( P. bornholmensis and P. islandica ) were described by Spencer (1976) and Ólafsson (1988), but they were synonymized with P. dorsata by Zlobin (2005). The taxonomic confusion would be caused by scarcity of specimens of these rare species and lack of information on their biology. Our numerous reared specimens and extensive records of host plants suggest that bryophyte-associated Phytoliriomyza species are diverse, and that the synonymized species may be definite species circumscribed by external and genital morphology.

This species resembles P. brunofasciata in having two pairs of dark lateral stripes on the scutum, but it is distinguished from P. brunofasciata by the dark-sided scutellum (scutellum wholly yellow in P. brunofasciata ) and the number of tubercle-like setae on the surstylus of the male epandrium (two in P. dorsata ; one in P. brunofasciata ).

Figures

Figure 1. Phytoliriomyza dorsata A-E male at Yakumo A habitus B lateral body C frontal head D dorsal thorax E thorax in posterior view F, G female at Yakumo F dorsal thorax G lateral body H-J male genitalia H whole genitalia, ventral I phallic complex, ventral J epandrium, ventral K, L female postabdomen K oviscape and spermatheca L tergite 10 M-O mined thalli of Marchantia polymorpha M mined thallus dissected to show interior and puparium (arrow) N mined thallus with exit hole O the same thallus with the mine dissected to show a puparium (arrow).

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