34. Phytoliriomyza ricciae Kato sp. nov.

Figs 63, 64

Material examined.

Holotype: Japan: 1♂ (MK-AG-a416), Iwakura-muramatsu, Sakyo-ku, Kyoto Pref. (35.0931°N, 135.7900°E, 150 m asl), 12-XI-2020 (as larva on Riccia huebeneriana), emerged on 1-XII-2020, NSMT-I-Dip 32091. Paratypes: Japan: 1♂1♀ (MK-AG-a477, a478), same data as holotype, emerged on 2-16-XII-2020, NSMT-I-Dip 32092-32093; 1♀ (MK-AG-201), type locality, 27-X-2017 (as larva on R. huebeneriana), emerged on 13-XI-2017, NSMT-I-Dip 32094; 1♀ (MK-AG-205), Muramatsu, Iwakura, Sakyo-ku, Kyoto Pref., 16-XI-2017 (as larva on R. nipponica), emerged on 8-XII-2017, NSMT-I-Dip 32095; 1♀ (MK-AG-234), Niken-chaya, Shizuichi-ichihara, Sakyo, Kyoto Pref., 18-XII-2015 (as larva on R. nipponica), emerged on 15-IV-2016, NSMT-I-Dip 32096;1♂ (MK-AG-a440), Nienami, Nango, Nichinan, Miyazaki Pref., 25-IX-2017 (as larva on R. canaliculata), emerged on 29-X-2017, NSMT-I-Dip 32097.

Other material.

Japan: On R. nipponica: 39♂40♀, Niken-chaya, Shizuichi-ichihara, Sakyo, Kyoto Pref., 31-X-2015 (as larva), emerged on 25-XI-2015-8-IV-2016; 1♀, Midai-gawa. Tatsuoka, Nirasaki, Yamanashi Prec., 10-XII-2016 (as larva), emerged on 14-V-2017.

On R. miyakeana: 1♀, Muramatsu, Iwakura, Sakyo-ku, Kyoto Pref., 16-XI-2017 (as larva), emerged on 10-XII-2017.

On R. lamellosa: 1♂, Joja, Joso, Ibaragi Pref., 2-XI-2021 (as larva), emerged on 3-XII-2021.

On R. oryzicola: 1♂, Somada, Wazuka, Soraku, Kyoto Pref., 15-X-2021 (as larva), emerged on 15-XI-2021; 1♀, Megami, Makinohara, Shizuoka Pref., 20-X-2017 (as larva), emerged on 3-I-2018; 1♀, Aono-gawa, Sanda, Hyogo Pref., 30-X-2017 (as larva), emerged on 26-XI-2017.

On R. bifurca: 1♂, Inago, Shibakawa, Fujinomiya, Shizuoka Pref., 10-X-2021 (as larva), emerged on 21-X-2021.

On R. huebeneriana: 2♀, Muramatsu, Iwakura, Sakyo-ku, Kyoto Pref., 16-X-2017 (as larva), emerged on 8-18-XII-2017; 1♂1♀, Mt. Osuzu, Tsuno, Miyazaki Pref., 24-IX-2017 (as larva), emerged on 15-X-2017; 1♂1♀, Urauchi, Iriomote-Is. Yaeyama, Okinawa Pref., 9-XI-2021 (as larva), emerged on 30-XI-2021; 1♂, Nametoko, Matsuno, Kita-uwa, Ehime Pref., 3-X-2021 (as larva), emerged on 20-X-2021; 3♀, Kayo, Nago, Okinawa Pref., 10-XI-2021 (as larva), emerged on 22-28-XI-2021.

On R. canaliculata: 3♂, Nienami, Nango, Nichinan, Miyazaki Pref., 25-IX-2017 (as larva), emerged on 17-29-IX-2017.

Diagnosis.

A small species (wing length 1.0-1.3 mm) having a pruinose grayish yellow scutum with a medial and two pairs of lateral dark gray stripes, a gray scutellum, yellow pleuron, black 1st flagellomere, dark maxillary palpus, yellowish gray halteres, and yellow legs. Male epandrium with dorso-ventrally bilobed surstylus; dorsal arm with two short tubercle-like setae. Male epandrium with bilobed, dorsoventrally elongated surstyli. Distiphalli tapering toward apex and bilaterally asymmetrical. Larva mines the thallus of Riccia spp.

Description.

Adult male (Fig. 63A-E).

Head: Head entirely light yellow, with ocellar tubercle dark brown, and back of head dark brown (Fig. 63C). Antenna porrect; first flagellomere dark brown with arista base yellowish, pedicel and scape grayish yellow (Fig. 63B). Arista subbasal, brown, pubescent. Frons brownish yellow, with reflective pruinosity. Face, gena, parafacial and postgena yellow. Proboscis normal, yellow; palpus dark brown, dorso-ventrally flattened, spatula-shaped (Fig. 63C). Chaetotaxy: Front orbitals three pairs; one ori directed inward; two ors directed upward (Fig. 63B). Orbital setulae minute and proclinate, in a single row.

Thorax: Thorax pruinose light yellow. Scutum grayish yellow with medial blackish stripe on anterior 2/3, one pair of blackish suborbicular presutural spots confluent with the medial blackish stripe, a pair of narrow blackish supra-alar stripes, and a pair of wider blackish intra-alar stripes, which adjoin the pair of lateral presutural suborbicular spots (Fig. 63D). The background color of the scutum is paler in live than in dried specimens. Scutellum gray. Subscutellum yellow except brown posterior half. Mediotergite dark gray, anatergite and katatergite light yellow (Fig. 63E). Pleuron largely light yellow; postpronotal lobe with anterior brown spot; propleuron with a small brown patch on mid-anterior corner; anepisternum and anepimeron light yellow; katepisternum and meron with large brown patches on venter (Fig. 63B). Haltere yellowish gray, with stalk light yellow. Calypter margin and hairs gray. Leg segments yellow; tibia and tarsus darker (Fig. 63A). Chaetotaxy: Scutum with 1+3 dorsocentrals, shortened anteriorly (Fig. 63D). Acrostichal setulae almost absent or with one (or rarely two) pair of minute setae. Wing: Wing length 1.4 mm, costa reaching M1 (Fig. 63A). M4 disappears immediately before reaching wing margin. Length of ultimate section of vein M4 divided by penultimate section 2.2-2.4.

Abdomen: Abdomen dorsally subshiny grayish yellow; epandrium dark brown (Fig. 63E). Genitalia: (Fig. 63G-K) Epandrium rounded apically; posterior end of inner margin with two or three short tubercle-like setae directed ventrally (Fig. 63G, K). Surstylus dorso-ventrally bilobed; dorsal lobe broad with two bulbous tubercle-like setae apically; ventral lobe narrow with three or four long setae apically (Fig. 63K). Cercus narrow, setose. Subepandrial sclerite pale, plate-like (Fig. 63K). Hypandrium thin, slightly sclerotized along outer margin (Fig. 63G). Postgonite bare, goose barnacle-shaped, rounded apically (Fig. 63I). Phallophorus with shallow incision below, articulated with phallapodeme, fused to epiphallus (Fig. 63H, I). Basiphallus dorsally sclerotized, with a pale narrow sclerite on left side (Fig. 63I). Hypophallus membranous and trilobed, with a pair of small dark lobate sclerites basally (Fig. 63H). Mesophallus pale cylindrical and laterally pigmented (Fig. 63H). Distiphallus comprising one pair of bilaterally asymmetrical tubules; tubule tapering toward apex; right one shorter and thicker than left one (Fig. 63H, I). Ejaculatory apodeme pale brown, fan-shaped with short stalk and clear sperm pump (Fig. 63J).

Female (Fig. 63F). Similar to male, but slightly larger and frons wider. Wing length 1.4 mm. Postabdomen: (Fig. 64A, B) Oviscape dark brown, setigerous (Fig. 64A). Tergite 10 cruciform, laterally uniting narrow pleural sclerites (Fig. 64B). Each cercus with two stout, apical, trichoid sensilla, 1/2 length of cercus (Fig. 64B). Spermathecae semi-orbicular, with truncate proximal ends (Fig. 64A).

Variation.

Geographical variation was found in the presence of an acrostichal seta on the scutum; the seta was almost absent in individuals at most localities but present in those from the Okinawa Island.

Immatures. (Fig. 64G-K, O) Puparium internal, slender and dark brown (Fig. 64O).

Etymology.

The specific name refers to the host plant genus Riccia .

Japanese name.

Yosame-hatakegoke-hamoguribae.

Host plants.

Riccia nipponica (Fis. 64G), R. miyakeana (Fig. 64H, I), R. oryzicola (Fig. 64J-L), R. bifurca, R. lamellosa, R. huebeneriana (Fig. 64M) and R. canaliculata (Fig. 64N) ( Ricciaceae). Although the European species, P. mesnili has been recorded from Riccia and Ricciocarpos, P. ricciae has been recorded only from Riccia spp., even though Ricciocarpos natans was abundant in the same rice fields.

Mine.

(Fig. 64G-N) Larvae constructed linear-blotch mines in the thallus from autumn to winter, and pupated inside or outside the mines. This variation in pupation site is due to the thalli of the host plants being small and thin; only the surface layer of the thalli remained intact, with internal parenchymatous tissues largely consumed. The larvae sometimes transfer to neighboring/overlapping thalli and fed on them.

Biological notes.

The host liverwort species, R. nipponica, R. miyakeana, R. oryzicola and R. huebeneriana grow only in the paddy fields that have not experienced land improvement projects or spraying herbicides (Fig. 64D-F). Thus, P. ricciae is now rare and threatened due to decrease of its potential habitats, and additionally due to recent overuse of insecticides. Because the host liverworts appear in paddy fields only after harvest of rice in autumn, it is unknown how the species pass other seasons from spring to autumn. The rice fields applied with organic farming also harbors various hornwort species, and harbor hornwort-associated species, P. phaeocerotis .

Distribution.

Japan: Honshu, Shikoku, Kyushu, Okinawa Is. and Iriomote Is. (Fig. 65).

Remarks.

This species resembles an European Ricciocarpos / Riccia -associated species, P. mesnili; it is distinguished from the latter by the dark color of scutum and scutellum (paler in P. mesnili), the obscure dark lateral bands on scutum (more distinct in P. mesnili), the vestigial acrostichal seta (almost absent in P. ricciae; with four pairs of acrostichal setae in P. mesnili), the small hypophallus (developed and sclerotized in P. mesnili; hypophallus is reported as paraphallus in Sellier 1947).

This species is also closely related to another European species, P. venustula Spencer (host unknown); it is distinguished from the latter by the vestigial acrostichal setae on the scutum (present in P. venustula), weaker sclerotization of male genitalia (well sclerotized in P. venustula), number of apical long setae on the ventral lobe of the surstylus (3-4 in P. ricciae; 6 in P. venustula), and the small but distinct hypophallus (hypophallus lacking in P. venustula).

Among the Japanese species, P. ricciae resembles P. suetsugui, P. sexfasciata, and P. megacerotis in having wholly dark scutum and dark maxillary palpus; it is distinguished from them by the absence of a comb of tubercle-like setae on the male epandrium. This species also resembles P. ugetsu, P. caerulescens, and P. phaeocerotis in having a wholly dark scutum; it is distinguished from them by the color of maxillary pulps (dark in P. ricciae; yellow in the others).