Phytoliriomyza crepusculum 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

7. Phytoliriomyza crepusculum Kato sp. nov.

Fig. 13.

Material examined.

Holotype: Japan: 1♂ (MK-AG-a29), Naiku, Oe, Fukuchiyama, Kyoto Pref. (35.433016°N, 135.150397°E, 75 m asl), 17-III-2017 (as larva), emerged on 17-V-2017, NSMT-I-Dip 31929. Paratypes: Japan: 1♂ (MK-AG-a457), type locality, 19-V-2021 (as larva), on 1-VII-2021, NSMT-I-Dip 31930; 1♂1 ♀ (MK-AG-a399, 274), Inago, Shibakawa, Fujinomiya, Shizuoka Pref., 17-II-2002 (as larva), emerged on 17-23-IV-2002, NSMT-I-Dip 31931, 31932; 1♂ (MK-AG-a309), Mitake, Kamitsushima, Nagasaki Pref., 19-IV-2009 (as larva), emerged on 6-VI-2009, NSMT-I-Dip 31933.

Other material.

Japan: 1♀, Sanekawa-keikoku, Iide, Aga, Higashikanbara, Niigata Pref., 3-V-2015 (as larva), emerged on 12-VI -2015; 1♀, Mt. Kiyosumi, Kamogawa, Chiba Pref., 24-I-2012 (as larva), emerged on 25-V-5-VI-2012; 17♂32♀, Inago, Shibakawa, Fujinomiya, Shizuoka Pref., 17-II-2002 (as larva), emerged on 23-IV-5-VI-2021; 1♂, Shogawa-kyo, Tonami, Toyama Pref., 3-V-2016 (as larva), emerged on 9-VI -2016; 1♀, Takeda-gawa, Maruoka, Sakai, Fukui Pref., 6-IV-2002 (as larva), emerged on 13-VI-2019; 2♂2♀, Mt. Nabejiri, Taga, Shiga Pref., 23-V-2015 (as larva), emerged on 26-15-VI-2015; 1♂1♀, Boumura, Kazuragawa, Otsu, Shiga Pref., 7-IV-2002 (as larva), emerged on 24-V-2002; 1♂1♀, Mitake, Kamitsushima, Nagasaki Pref., 9-IV-2009 (as larva), emerged on 6-VI-2009.

Diagnosis.

A medium-sized species (wing length 1.4-1.8 mm) having subshiny brown scutum with brownish yellow pattern extending from mid-posterior margin to scutellum, black 1st flagellomere, brown maxillary palpus, brown halteres, and brownish yellow legs. Male epandrium inner-laterally with a comb comprising five long fused tubercle-like setae. Larva mines the thallus of Dumortiera hirsuta .

Description.

Adult male (Fig. 13A-D ).

Head: Head largely light yellow; ocellar triangle yellow but ocellar tubercle dark brown; back of head dark brown above foramen excluding margin (Fig. 13C ). Antenna porrect, first flagellomere black, pedicel and scape yellow. Arista subbasal, pubescent. Face, gena, parafacial and postgena light yellow. Proboscis normal, yellow; palpus yellow, cylindrical. Chaetotaxy: Front orbitals three pairs; one ori directed inward; two ors directed upward (Fig. 13B ). Orbital setulae minute and erect, in a single row.

Thorax: Thorax subshiny. Scutum brown with a large posterior trapezoid yellow patch adjacent to scutellum (Fig. 13D ). Scutellum yellow with lateral corner narrowly brown. Subscutellum yellow. Mediotergite, katatergite and anatergite brown. Pleuron yellow, but propleuron, meron, anepimeron centrally pale brown (Fig. 13B ). Haltere brown. Calypter margin and hairs gray. Leg segments yellow; tibia and tarsus dorsally brown (Fig. 13D ). Chaetotaxy: Scutum with 1+3 dorsocentrals, shortened anteriorly (Fig. 13D ). Acrostichal setulae five pairs in two rows. Wing: Wing length 1.4 mm, costa reaching M1 (Fig. 13A ). Length of ultimate section of vein M4 divided by penultimate section 1.1.

Abdomen: Abdomen dorsally subshiny brown (Fig. 13D ). Genitalia: (Fig. 13F-I ) Epandrium dark brown, rounded apically; posterior end of inner margin with a stout tubercle-like seta; inner-ventral surface of epandrium with a comb comprising five fused long tubercle-like setae; inner-ventral margin with a row of several short tubercle-like setae (Fig. 13I ). Surstylus rounded, directed inwards, setose apically but without tubercle-like seta. Cercus narrow, setose. Subepandrial sclerite with one pair of posteriorly directed plate-like arms (Fig. 13I ). Hypandrium slightly sclerotized along outer margin (Fig. 13G ). Postgonite bare, goose barnacle-shaped, narrowly rounded, and cleft apically (Fig. 13H ). Phallophorus with deep incision below (Fig. 13G ), and articulated with phallapodeme, fused to epiphallus (Fig. 13H ). Basiphallus composing of a left anterodorsal sclerite and a right L-shaped lateral sclerite; former narrow, protruding rightward, the latter protruding ventrally (Fig. 13G-H ). Hypophallus broad and membranous, supported by one pair of fused sclerites ventrally (Fig. 13G, H ). Mesophallus dark, cylindrical, widest subbasally, slightly shorter than distiphallus (Fig. 13H ). Distiphallus consists of a pair of moderately long tubules slightly diverging apically; basal half composed of dark narrow lobate sclerite and weaker medial region; distal half cylindrical, dorsally pigmented, with truncated, unpigmented apex (Fig. 13H ). Ejaculatory apodeme fan-shaped with short broad stalk, broad base, and clear sperm pump (Fig. 13F ).

Female (Fig. 13E ). Similar to male (Fig. 13E ). Wing length 1.4-1.8 mm. Postabdomen: (Fig. 13K, L ) Oviscape brown sparsely setigerous on lateral sides (Fig. 13K ). Tergite 10 trifurcate, laterally uniting narrow pleural sclerites (Fig. 13L ). Cercus with two stout, apical, trichoid sensilla, ca. 1/2 length of cercus (Fig. 13L ). Spermathecae semi-orbicular, with truncate proximal ends (Fig. 13K ).

Immatures. (Fig. 13J ) Puparium internal, slender, and pale brown.

Etymology.

The specific name (crepusculum = twilight) refers to the brownish yellow patch on the scutum.

Japanese name.

Yuuzuki-kezenigoke-hamoguribae.

Host plant.

Dumortiera hirsuta ( Dumortieraceae ).

Mine.

(Fig. 13N-P ) Larvae mine the midrib of the thallus in early instars, later construct radiate mines by coming out from the midrib, and pupate in the mines. Puparium is smooth and pale brown, posterior spiracles projecting (Fig. 13J ).

Biological notes.

The main habitats of this species are along streams in warm temperate forests and cool temperate deciduous forests (Fig. 13M ), and this species was sympatric with P. dumortierae in some localities. Our rearing records suggest that this species is univoltine, and that adults emerge from overwintered pupae in spring.

Distribution.

Japan: Honshu, Shikoku, Kyushu, Tsushima Island (Fig. 12 ).

Remarks.

Although this species used the same host plant as P. dumortierae , these two species were not sympatric in any localities. This species resembles P. arcus , P. plagiochasmatos and P. falcata in having a pair of brown lateral bands on the scutum; it is distinguished from them by the brownish yellow color of the medial mark on scutum (light yellow in the other species).

Species associated with Plagiochasma

Figures

Figure 12. Locality records of three Phytoliriomyza species associated with Dumortiera spp.: P. dumortierae and P. crepusculum.

Figure 13. Phytoliriomyza crepusculum sp. nov. A-C holotype male A habitus B lateral C frontal D paratype male (MK-AG-a 309), dorsal E paratype female (MK-AG- 274), dorsal F-I male genitalia F ejaculatory apodeme, dorsal G whole genitalia, ventral H phallic complex, lateral I epandrium, ventral J puparium K-L female postabdomen K oviscape and spermatheca L tergite 10 M habitat of type locality N-P mined thalli of Dumortiera hirsuta (N type locality O Kiyosumi P Mt. Nabejiri). An arrow in N indicate an puparium.