Phytoliriomyza iriomotensis 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

11. Phytoliriomyza iriomotensis Kato sp. nov.

Fig. 20

Material examined.

Holotype: Japan: 1♂ (MK-AG-161), Yutsun, Iriomote-Is. Yaeyama, Okinawa Pref. (24.379°N, 123.883°E, 15 m asl), 25-I-2011 (as larva), emerged on 23-IV-2011, NSMT-I-Dip 31949. Paratypes: Japan: 2♀ (MK-AG-164, a426), same data as holotype, emerged on 2-10-III-2011, NSMT-I-Dip 31950, 31951; 1♂1♀ (MK-AG-a591, a592), type locality, 18-XI-2021 (as larva), emerged on 16-21-XI-2021, NSMT-I-Dip 31952, 31953.

Other material.

Japan: 1♀, Yutsun, Iriomote-Is. Yaeyama, Okinawa Pref., 8-XI-2021 (as larva), emerged on 17-XI-2021.

Diagnosis.

A small species (wing length 1.4-1.7 mm) having pruinose gray scutum and scutellum, brown 1st flagellomere, yellow maxillary palpus, dark halteres, and yellow legs. Scutum lacks acrostichal setulae. Male epandrium lacks tubercle-like seta; distiphallus of male genitalia tapering apically. Larva mines the thallus of Asterella liukiuensis .

Description.

Adult male (Fig. 20A-E ).

Head: Head light yellow, with ocellar tubercle brown, frons brownish yellow, back of head dark brown (Fig. 20C ). Antenna porrect, first flagellomere, pedicel and scape brown (Fig. 20B ). Arista subbasal, black pubescent. Clypeus, face, gena, parafacial and postgena light yellow. Proboscis normal, light yellow; palpus light yellow, cylindrical (Fig. 20C ). Chaetotaxy: Front orbitals three pairs; one ori directed inward; two ors directed upward (Fig. 20D ). Orbital setulae minute and erect, in a single row.

Thorax: Thorax pruinose. Scutum and scutellum dark brown (Fig. 20B ). Mediotergite brown, anatergite with circular brown patches on venter, and katatergite yellow (Fig. 20E ). Pleuron largely pale yellow, katepisternum and meron with large brown patches on venter (Fig. 20B ). Haltere brown with pale yellow stalk. Calypter margin and hairs gray. Leg segments dark yellow; tibia and tarsus darker (Fig. 20A ). Chaetotaxy: Scutum with 1+3 dorsocentrals, shortened anteriorly (Fig. 20D ). Acrostichal setulae lacking. Wing: Wing length 1.4 mm, costa reaching M1 (Fig. 20A ). Length of ultimate section of vein M4 divided by penultimate section 2.0-2.4. M4 disappear before reaching wing margin.

Abdomen: Abdomen dorsally subshiny yellowish brown (Fig. 20E ). Genitalia: (Fig. 20G-J ) Epandrium dark brown, rounded apically; posterior end of inner margin with a tubercle-like seta; inner-lateral margin with three tubercle-like setae (Fig. 20H ). Surstylus elongated, broad basally, sparsely setose apically (Fig. 20H ). Cercus narrow, setose. Subepandrial sclerite comprising a pair of plate-like arms (Fig. 20H ). Hypandrium slightly sclerotized along outer margin (Fig. 20G ). Postgonite bare, goose barnacle-shaped, cleft apically; upper lobe pointed apically, lower lobe rounded (Fig. 20I ). Phallophorus with deep incision below, articulated with phallapodeme, fused to epiphallus (Fig. 20G, I ). Basiphallus longer than mesophallus, dorsally sclerotized (Fig. 20G ). Hypophallus broad, membranous, medially with a pair of fused sclerites (Fig. 20G, I ). Paraphallus absent. Mesophallus short, sclerotized dorsally and ventrally in basal 2/3; shorter than distiphallus (Fig. 20G, I ). Distiphallus comprising one pair of tubules; basal half dorsally pigmented, with small ventral sclerite basally, distal half unpigmented and tapering toward tip (Fig. 20G, I ). Ejaculatory apodeme pale and narrow fan-shaped with long stalk; base wide to one side; sperm pump clear (Fig. 20J ).

Female (Fig. 20F ). Similar to male, but slightly larger; scutum paler, abdomen dorsally paler, and legs paler than male. Wing length 1.7 mm. Postabdomen: (Fig. 20K ) Oviscape dark brown, setigerous. Each cercus with two stout, apical, trichoid sensilla, 1/3 length of cercus.

Etymology.

The specific name refers to the type locality, Iriomote Island.

Japanese name.

Okinawasaihaigoke-hamoguribae.

Host plant.

Asterella liukiuensis ( Aytoniaceae ).

Mine.

Larvae construct linear-blotch mines in the thallus in early instars, later entering the midrib, and pupating there (Fig. 20M-O ).

Biological notes.

The habitats of this species are rocky stream banks in subtropical evergreen forests (Fig. 20L ).

Distribution.

Japan (Honshu). Recorded only from Iriomote Island in the Ryukyu Archipelago (Fig. 21 ).

Remarks.

This species resembles P. ugetsu , P. ricciae and P. phaeocerotis in having a wholly dark scutum and yellow maxillary palpus; it is distinguished from P. ugetsu by its small size (wing length 1.4 -1.7 mm in P. iriomotensis ; 2.1-2.7 mm in P. ugetsu in wing length), and from P. ricciae and P. phaeocerotis by the dark brown legs (legs pale brown in the latter two species).

In Japan, six Asterella species are distributed in limited areas in central Honshu and Okinawa and Yaeyama Islands, and almost all of them are endangered ( Ministry of the Environment Japan 2015). It is remarkable that such rare liverwort species are associated with specific agromyzid species.

Species associated with Reboulia

Figures

Figure 20. Phytoliriomyza iriomotensis sp. nov. A-E holotype male A habitus B lateral C frontal D dorsal E posterodorsal F paratype female, dorsal (MK-AG- 426) G-J male genitalia G whole genitalia, ventral H epandrium, ventral I phallic complex, lateral J ejaculatory apodeme, lateral K female postabdomen L habitat at type locality M-O mined thalli of Asterella liukiuensis (an arrow indicates a larva).

Figure 21. Locality records of three Phytoliriomyza species associated with Asterella and Reboulia spp.: P. iriomotensis and P. cometiformis.