37. Phytoliriomyza foliocerotis Kato sp. nov.

Fig. 70

Material examined.

Holotype: Japan: 1♂ (MK-AG-a310), Mt. Osuzu, Tsuno, Miyazaki Pref. (32.251°N, 131.481°E, 150 m asl), 11-IV-2021 (as larva), emerged on 26-IV-2021, NSMT-I-Dip 32110. Paratypes: Japan: 1♂2♀ (MK-AG-a451, a449, a450), type locality, 14-VII-2021 (as larva), emerged on 1-6-VIII-2021, NSMT-I-Dip 32111-32113.

Other material.

Japan: 2♂1♀, Mt. Osuzu, Tsuno, Miyazaki Pref., 14-VII-2021 (as larva), emerged on 31-VII-18-VIII-2021.

Diagnosis.

A small species (wing length 1.1-1.3 mm) having a subshiny black scutum, black scutellum with small yellow spot centrally, yellow 1st flagellomere, yellow maxillary palpus, yellow halteres, and yellow legs. Male epandrium inner-laterally with one strong tubercle-like seta. Distiphalli tapering toward apex, fused after meeting, elongated over the length of phallapodeme. Larva mines the thallus of a hornwort, Folioceros fuciformis .

Description.

Adult male (Fig. 70A-D).

Head: Head light yellow, with ocellar tubercle dark brown, and back of head dark brown excluding margins (Fig. 70C). Antenna porrect; first flagellomere yellow, only narrow area around base of arista grayish; pedicel and scape yellow (Fig. 70B). Arista subbasal, brown, pubescent. Frons brownish yellow, with reflective pruinosity. Face, gena, parafacial and postgena light yellow. Proboscis normal, light yellow; palpus light yellow, ovate (Fig. 70C). Chaetotaxy: Front orbitals three pairs; one ori directed inward; two ors directed upward (Fig. 70D). Orbital setulae minute and proclinate, in a single row.

Thorax: Thorax subshiny. Scutum pruinose black (Fig. 70D). Scutellum black, medially with a small, obscure yellow patch. Subscutellum pale yellow. Mediotergite dark gray, anatergite brown, and katatergite pale yellow (Fig. 70B). Pleuron largely pale yellow; postpronotal lobe with anterior brown spot; propleuron with a small brown patch on mid-anterior corner; notopleuron with narrow brown patch on anterior-lower margin; anepisternum and anepimeron without brown spot; katepisternum and meron with large brown patches on venter (Fig. 70B). Haltere grayish yellow, with stalk paler. Calypter margin and hairs gray. Leg segments pale yellow; femur of foreleg with narrow brown subdistal patch frontally; tibia and tarsus darker (Fig. 70A). Chaetotaxy: Scutum with 1+3 dorsocentrals, shortened anteriorly (Fig. 70D). Acrostichal setae three or four pairs in two rows. Wing: Wing length 1.3 mm, costa reaching M1 (Fig. 70A). M4 disappears immediately before reaching wing margin. Length of ultimate section of vein M4 divided by penultimate section 1.7.

Abdomen: Abdomen dorsally subshiny yellowish brown; epandrium brown (Fig. 70E). Genitalia: (Fig. 70G-J) Epandrium rounded apically; posterior end of inner margin with one strong tubercle-like seta (Fig. 70J). Surstylus small, spatula-shaped, setose apically (Fig. 70J). Cercus narrow, setose. Subepandrial sclerite vestigial. Hypandrium thin, slightly sclerotized along outer margin (Fig. 70G). Postgonite bare, goose barnacle-shaped, rounded apically (Fig. 70I). Phallophorus with shallow incision below, articulated with phallapodeme, fused to epiphallus (Fig. 70I). Basiphallus with dark narrow dorsal sclerite and apically bilobed pale ventral sclerite (Fig. 70I). Hypophallus membranous with microtrichia, (Fig. 70I). Paraphallus absent. Mesophallus cylindrical, laterally and dorsally sclerotized, parallel-sided (Fig. 70I). Distiphallus comprising one pair of tubules, with dark dorsal shoehorn-shaped sclerites basally; the tubules thin, fused after meeting, elongated over the length of phallapodeme (Fig. 70G). Ejaculatory apodeme fan-shaped, with short broad stalk and dark base; sperm pump clear (Fig. 70H).

Female (Fig. 70E-F). Similar to male, but larger, frons wider. Wing length 1.1 mm. Postabdomen: (Fig. 70K, L) Oviscape dark brown, setigerous (Fig. 70K). Tergite 10 cruciform, laterally uniting narrow pleural sclerites. Each cercus with two stout, apical, trichoid sensilla, same length as cercus (Fig. 70L). Spermathecae semi-orbicular; with truncate proximal ends (Fig. 70K).

Etymology.

The specific name refers to the host plant genus Folioceros .

Japanese name.

Miyabetsunogoke-hamoguribae.

Host plant.

Folioceros fuciformis ( Anthocerotaceae).

Mine.

Mines are extremely inapparent because the thalli are thick and often overlapping (Fig. 70N).

Biological notes.

The habitat of this species is a cliff along a river bank in warm temperate evergreen forests dominated by Castanopsis sieboldii and Quercus helva (Fig. 70M), and the host hornwort grows with the liverwort Marchantia papillata grossibarba . Our rearing records suggest that this species is at least bivoltine, with adults emerging in April and August.

Distribution.

Japan: Kyushu (Fig. 71). Recorded only from the type locality.

Remarks.

This species resembles P. nubatama in having a shiny black dorsal scutum and a small yellow spot in the black scutellum; it is distinguished from the latter by the yellow 1st flagellomere of the antenna (dark in P. nubatama). These two species were found sympatrically at the type locality, where their host plants, Marchantia papillata grossibarba and Folioceros fuciformis, grow in similar riparian habitats. Irrespective of their similar external morphology, these species are evidently distantly related, given their greatly differing genital morphology.

The three agromyzid species recorded from hornworts all had a dark scutum, but varied among species in color of antenna, color of maxillary palpus, and comb of tubercle-like setae on male epandrium. They also had common characteristics in the male genitalia; the distiphallus is little sclerotized, elongated, and tapering toward the apex. These characteristics of the male genitalia in hornwort-associated species suggest their monophyletic origin.