Phytoliriomyza sexfasciata 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

35. Phytoliriomyza sexfasciata Kato sp. nov.

Fig. 66 , 67

Material examined.

Holotype: Japan: 1♂ (MK-AG-a574), Ookura, Arashiyama, Hiki, Saitama Pref. (36.0276°N, 139.3284°E, 50 m asl), 2-XI-2021 (as larva on Riccia lamellosa ), emerged on 25-XI-2020, NSMT-I-Dip 32098. Paratypes: Japan: 1♂2♀ (MK-AG-a573, a583, a584), same data as holotype, emerged on 17-25-XI-2021, NSMT-I-Dip 32099-32101; 1♀ (MK-AG-a568), Joja, Joso, Ibaragi Pref., 2-XI-2021 (as larva on Riccia lamellosa ), emerged on 19-XI-2021, NSMT-I-Dip 32102; 1♂ (MK-AG-a585), Joja, Joso, Ibaragi Pref., 10-X-2021 (as larva on Riccia bifurca ), emerged on 8-XI-2021, NSMT-I-Dip 32103.

Other material.

Japan; On R. lamellosa :11♂14♀, Negishi, Arashiyama, Hiki, Saitama Pref., 2-XI-2021 (as larva), emerged on 17-XI-12-XII-2021; 3♂5♀, Joja, Joso, Ibaragi Pref., 2-XI-2021 (as larva, emerged on 17-25-XI-2021.

On R. bifurca : 7♂9♀, Joja, Joso, Ibaragi Pref., 2-XI-2021 (as larva), emerged on 8-29-XI-2021.

On R. sorocarpa : 3♂3♀, Joja, Joso, Ibaragi Pref., 2-XI-2021 (as larva), emerged on 22-XI-26-XII-2021.

Diagnosis.

A small species (wing length 1.2-1.5 mm) having a pruinose grayish scutum with six longitudinal dark gray bands, a gray scutellum, brown 1st flagellomere, brown maxillary palpus, yellowish gray halteres, and yellow legs. Male epandrium inner-distally with a strong tubercle-like seta and inner-basally with a cluster of 29-35 dense tubercle-like setae. Distiphalli bilaterally asymmetrical, with left one tapering toward apex. Larva mines the thallus of Riccia lamellosa , R. sorocarpa and R. bifurca .

Description.

Adult male.

Head: (Fig. 66A-E ) Head largely light yellow, with ocellar tubercle dark brown, and back of head dark brown (Fig. 66C ). Antenna porrect; first flagellomere dark brown, pedicel and scape brown (Fig. 66B ). Arista subbasal, brown, pubescent. Frons brownish yellow, with reflective pruinosity (Fig. 66C ). Face, gena, parafacial and postgena light yellow. Proboscis normal, light yellow; maxillary palpus light yellow, cylindrical (Fig. 66C ). Chaetotaxy: Front orbitals three pairs; one ori directed inward; two ors directed upward (Fig. 66B ). Orbital setulae minute and proclinate, in a single row.

Thorax: Thorax pruinose gray. Scutum gray with three pairs of longitudinal dark gray stripes, with the four inner stripes continuing into dark gray bands of gray scutellum (Fig. 66D ). Subscutellum light yellow except brown posterior half. Mediotergite dark gray, anatergite and katatergite light yellow (Fig. 66E ). Pleuron largely light yellow; postpronotal lobe with anterior brown spot; propleuron, light yellow; anepisternum light yellow with L-shaped anterior brown spot; anepimeron light yellow with an upper linear macule and a lower spot; katepisternum and meron with large brown patches on venter (Fig. 66C ). Haltere yellowish gray, with stalk light yellow. Calypter margin and hairs gray. Leg segments brown; tibia and tarsus darker; distal half of femur of foreleg darkened on frontal side (Fig. 66A ). Chaetotaxy: Scutum with 1+3 dorsocentrals, shortened anteriorly (Fig. 66D ). Acrostichal setae 1-3 pairs in two rows. Wing: Wing length 1.2 mm, costa reaching M1 (Fig. 66A ). Length of ultimate section of vein M4 divided by penultimate section 2.0-2.3.

Abdomen: Abdomen dorsally subshiny brownish yellow, with a medial brown longitudinal band; epandrium brown (Fig. 66E ). Genitalia: (Fig. 66K-O ) Epandrium rounded apically; posterior end of inner margin with two tubercle-like setae, the dorsal one stouter and longer; inner-lateral surface with a dense cluster of 29-35 short tubercle-like setae (Fig. 66L ). Surstylus narrow and elongated, with 12-14 strong setae apically (Fig. 66L ). Cercus narrow, setose. Subepandrial sclerite pale, plate-like (Fig. 66L ). Hypandrium thin, slightly sclerotized along outer margin (Fig. 66K ). Postgonite bare, goose barnacle-shaped, cleft apically (Fig. 66M ). Phallophorus with shallow incision below, articulated with phallapodeme, fused to epiphallus (Fig. 66K ). Basiphallus with a dark dorsal narrow sclerite, the distal lobes of which extended laterally; 2-2.5 × as long as mesophallus (Fig. 66M, N ). Hypophallus broad and membranous, medially with a pair of dark, fused, ventrally incurved sclerites (Fig. 66M ). Mesophallus with a pair of short basal, ventral sclerites and a pair of dark, long, ventral sclerite (Fig. 66M ). Distiphallus comprising one pair of bilaterally asymmetrical dark tubules; left tubule longer than the right one, dorsally pigmented, tapering out; right tubule dorsally pigmented, truncated distally and bifid (Fig. 66M, N ). Ejaculatory apodeme pale brown and fan-shaped with constricted stalk; base dark and elongated to one side; sperm pump sausage-shaped, clear (Fig. 66O ).

Female (Fig. 66F-J, P ). Similar to male, but slightly larger and frons wider; color of pleuron, hind abdomen and legs much paler. Wing length 1.5 mm. Postabdomen: (Fig. 67A-C ) Oviscape dark brown, setigerous (Fig. 67B ). Tergite 10 cruciform, laterally uniting narrow pleural sclerites (Fig. 67C ). Each cercus with two stout, apical, trichoid sensilla, 1/2 length of cercus (Fig. 67C ). Spermathecae semi-orbicular, with truncate proximal ends (Fig. 67A ).

Immatures. (Fig. 67D-F, N, O ) At 3rd instar, larval body yellow and cylindrical. Mandibles paired, fused, asymmetrical and strongly sclerotized, each with two teeth; left teeth larger than right ones. Mandibles confluent with short sclerotized hypopharyngeal sclerite, connecting to a pair of sclerotized tentoropharyngeal sclerites; dorsal cornu broad and long, ventral cornu shorter, comprising two fused arms; upper arm dark sclerotized only in anterior half.

Etymology.

The specific name (sex = six, fasciatus = stripe) refers to the six dark gray stripes on the scutum.

Japanese name.

Mutsusuji-hatakegoke-hamoguribae.

Host plants.

Riccia lamellosa , R. bifurca , and R. sorocarpa .

Mine.

Larvae construct linear-blotch mines in the thallus, and pupate in or out of the mines (Fig. 67I-L ). Larvae sometimes relocate to fresh thalli as with P. ricciae .

Biological notes.

The host liverwort species, Riccia lamellosa , R. bifurca , and R. sorocarpa grow on bare mesic soil in orchards, parks, shrines and levees of paddy fields (Fig. 67G, H ). While R. lamellosa is a recently naturalized alien species ( Furuki 2000), the other hosts are native. Larvae of P. sexfasciata are found mining thalli of these liverwort species in early November, and adults emerge in late November.

Distribution.

Japan: Honshu (Fig. 65 ). So far, recorded only from alluvial plains in the Kanto Region.

Remarks.

This species is unique in that the scutum is six-banded (medial bands on the scutum are confluent in other species), and in the male epandrium having a clump (not a comb) of 25-30 short tubercle-like setae on the basal margin. This species resembles P. suetsugui , P. ricciae and P. megacerotis in having a wholly dark scutum and dark maxillary palpus, but is distinguished from them by the above-mentioned genital characteristics. It also resembles P. ugetsu , P. caerulescens and P. phaeocerotis in having wholly dark scutum, but is distinguished from them by the color of the maxillary palpus (dark in P. sexfasciata ; yellow in the others).

Figures

Figure 65. Locality records of three Phytoliriomyza species associated with Riccia spp.: P. ricciae, P. sexfasciata and P. caerulescens.

Figure 66. Phytoliriomyza sexfasciata sp. nov. A-E holotype male A habitus B lateral C frontal D dorsal E posterior F-J paratype female (MK-AG-a 573) F habitus F lateral G frontal H dorsal I posterior K-O male genitalia K whole genitalia, ventral L epandrium, ventral M phallic complex, lateral N genitalia, lateral O ejaculatory apodeme, lateral P live female fly walking on soil.

Figure 67. Female morphology and larval morphology / ecology of Phytoliriomyza sexfasciata sp. nov. A-C female postabdomen A spermatheca B oviscape and spermatheca C tergite 10 D-F Pharyngeal skeleton of 3 rd larva D lateral E dorso-lateral F dorsal G, H habitat (G at Joso H at type locality) I-L mined thalli and mining larvae (I-K Riccia lamellose at type locality L R. bifurca at Joso).