Ametrodiplosis stellariae Elsayed, Yukawa & Tokuda, 2021

Elsayed, Ayman Khamis, Yukawa, Junichi, Mochizuki, Ko, Tokuda, Makoto & Kawakita, Atsushi, 2021, Three new species of Ametrodiplosis (Diptera: Cecidomyiidae) from Japan, with a key to the Japanese species and a molecular phylogenetic analysis, Zootaxa 4942 (2), pp. 151-172 : 165-166

Ametrodiplosis stellariae Elsayed, Yukawa & Tokuda , n. sp.

[ Figures 8, 9 & 46–62 ]

This species is morphologically similar to A. adetos except for the following characters:

Adult. Head ( Figs 46–51 ): Frons with 5–7 setae (n = 5). Internode of male flagellomeres bare, evanescing after flagellomere IX. Mouthparts: labrum with 5–6 short setae (n = 6); labellum with 6–9 strong setae (n = 6).

Thorax. Wing ( Figs 8, 9 ) 2.2–2.6 mm long in females (n = 4), 2.0– 2.1 mm long in males (n = 3). Acromere ( Fig. 52 ): empodia nearly as long as claws. Scutellum laterally with 5–9 setae (n = 6). Anepimeron with 5–7 setae (n = 6); anepisternum with 2–4 scales (n = 6).

Female abdomen ( Figs 53, 54 ). Tergites I–VI with few lateral setae, few scattered scales on midlength and 1 row of posterior setae; tergite VII with few lateral setae and few scattered on 2 rows of posterior setae. Ovipositor: cerci, about twice longer than wide, with short setae on distal half.

Male abdomen ( Figs 55–57 ). Tergites without scales; tergite 7 with 1–2 setae placed posterolaterally. Terminalia: Basal portion of aedeagus extending anteriorly beyond baseline of gonocoxites.

Pupa ( Figs 58, 59 ). Antennal bases with pigmented, short, pointed protuberances. Prothoracic spiracle 26 μm long (n = 1), ca. 4.3 times longer than cephalic seta. Terga II–VIII with 3–4 horizontal rows of spine-like spicules on anteromedian third of segment.

Larva. Third instar ( Figs 60–62 ). Orange in life. Spatula with pointed lobes. Anus surrounded by median perineal pads covered with pointed and raised cuticular warts. Corniform terminal papillae similar in length; most anterior 2 corniform papillae thinner than others.

Etymology. The species name, stellariae , is based on the host genus name.

Holotype. 1♂ ( ELKU): Reared by R. Sonobe and emerged on 5.viii.2019 from a leaf bud gall on Stellaria uliginosa collected by R. Sonobe in Ryuzu, Nikko, Tochigi Prefecture, Japan on 16.vii.2019.

Paratypes. All collected and reared from leaf bud galls on Stellaria uliginosa in Japan; 2 third instar larvae: collected on 16.xi. 2014 in Yakumo village, Matsue City , Shimane Prefecture by T. Nodue. 2♂♂ 5♀♀: same as the holotype. 1 pupa: collected on 14.x.2016 by R. Sonobe at the type locality. 1 pupa & 4♂♂ 1♀: same as the holotype, but collected on 9–15.xi.2016 .

Distribution. Japan, Honshu: Tochigi, Shiga, Nara, Hiroshima, and Shimane Prefectures.

Life history and biological notes. Ametrodiplosis stellariae induces leaf bud galls on Stellaria uliginosa ( Fig. 3 ). Usually one, sometimes two or more larvae develop in each gall. Larva usually pupates in the gall but occasionally in the soil. The number of annual generations has not been clarified. A similar sort of leaf bud gall was found on two congeneric plant species, Stellaria sessiliflora Y. Yabe , in Nara and Tokushima Prefectures, and Stellaria uchiyamana Makino var. apetala (Kitam.) Ohwi in Nara Prefecture. In addition, Cerastium fontanum Baumg. (Caryophyllaceae) also bears similar leaf bud galls in Hokkaido. The host range of A. stellariae requires further study.

Remarks. One European species of Ametrodiplosis is presently known from Stellaria L., namely A. duclosii (Tavares) that induces leaf bud galls on S. graminea L. in France and Germany ( Tavares 1930; Stelter 1961; Gagné & Jaschhof 2017). Ametrodiplosis stellariae is distinct from A. duclosii as follows: the gonocoxite of A. stellariae are much narrower, its mediobasal lobe are closer to the gonocoxal bases but closer to the distal parts of gonocoxites in A. duclosii ( Stelter 1961) , and the anterior lobes of the larval spatula are more pointed in A. stellariae ( Tavares 1930) .

Ametrodiplosis stellariae is most similar to A. mamajevi and A. adetos with which they share the curved R 5 distally, narrow gonocoxites and mediobasal lobes placed on the basal half of gonocoxites ( Kovalev 1972). Ametrodiplosis stellariae can be distinguished from A. adetos by the less pronounced mediobasal lobe, the basal portion of aedeagus that exceeds anteriorly beyond the base line of gonocoxite, the short-pointed protuberance on pupal antennal bases, the narrow anterior lobes of larval spatula and the more elongate corniform terminal papillae in third instars. Ametrodiplosis stellariae differs from A. mamajevi as follows: the male hypoproct is deeply notched in A. stellariae , but shallowly notched in A. mamajevi ; male cerci are truncate in A. stellariae , but lobes of cerci trapezoid in A. mamajevi ; male flagellomere XII ends with narrow apical prolongation in A. stellariae but without such prolongation in A. mamajevi .

Figures

FIGURES 4–9. Female and male wings of Japanese Ametrodiplosis species. 4–5. Female and male wings of A. adetos n. sp., respectively. 6–7. Female and male wings of A. aeroradicis n. sp., respectively. 8–9. Female and male wings of A. stellariae n. sp., respectively. Scale bars = 50 µm.

FIGURES 46–52. Ametrodiplosis stellariae n. sp. 46. Head (left paplus is incomplete). 47. Ventral view of mouthparts. 48. Female antennal flagellomeres. 49. Male antennal flagellomeres. 50. Dorsal view of female flagellomere V. 51. Ventral view of male flagellomere V. 52. Tarsomere V and acromere. Scale bars = 50 µm.

FIGURES 53–57. Ametrodiplosis stellariae n. sp. 53. Female tergites VI–VII (left to right). 54. Ovipositor. 55. Male tergites VI–VII (left to right). 56. Ventral view of gonostylus. 57. Male terminalia. Scale bars = 50 µm.

FIGURES 58–62. Pupa and larva (third instar) of Ametrodiplosis stellariae n. sp. 58. Ventral view of pupal head. 59. Prothoracic spiracle in pupa. 60. Spatula. 61. Ventral view of larval terminal abdominal segments. 62. Dorsal view of larval terminal abdominal segments. Scale bars = 50 µm.

FIGURES 1–3. Ametrodiplosis species on their hosts in Japan. 1. Larvae of A. adetos n. sp. on a flower of Tylophora aristolochioides (Apocynaceae). 2. Aerial root galls (arrows) of A. aeroradicis n. sp. on Trachelospermum asiaticum (Apocynaceae). 3. Leaf bud gall of A. stellariae n. sp. on Stellaria uliginosa (Caryophyllaceae).