Palumbina pylartis (Meyrick, 1908)

Kyaw, Khine Mon Mon, Yagi, Sadahisa, Oku, Johei & Hirowatari, Toshiya, 2023, Taxonomic study of Palumbina Rondani (Lepidoptera, Gelechiidae, Thiotrichinae) in Japan: biology, immature stages, and a new species, ZooKeys 1165, pp. 61-99 : 61

Palumbina pylartis (Meyrick, 1908)

Figs 1A, B , 6A , 7A , 8A , 9A , 10 , 14 , 15 , 18 , 19 Japanese name: Minami-mongin-hoso-kibaga

Thiotricha pylartis Meyrick, 1908: 441. TL: Assam, India. TD: NHMUK.

Thyrsostoma pylartis : Meyrick 1925a: 100; Gaede 1937: 301; Inoue 1954: 67 (partim); Clarke 1969: 487; Moriuti 1982: 281, pl. 13-57 (partim); Kanazawa and Hepper 1992: 70.

Palumbina pylartis : Sattler 1982: 25; Sakamaki 2013: 298 (partim).

Material examined.

Japan - Honshu [Gifu] • 1♀; 20 Oct. 1919; gen. slide no. KM-333; ELKU. - [Wakayama] • 1♂; Kozagawa; 11 Jun. 1970; host: Castanopsis cuspidata ; T. Kumata; gen. slide no. KM-390; SEHU. • 2♀♀; same data except 9, 13 Jun. 1970; gen. slide no. KM-377; SEHU. - Kyushu [Fukuoka] • 1♀; Nishi-ku Fukuoka, Ito Campus; 27 Apr. 2017 larva; 1 Jun. 2017 em.; host: Castanopsis sieboldii ; T. Hirowatari, S. Yagi, C. Tsuji & K.M.M. Kyaw leg.; ELKU. • 1♂, 1♀; same locality, 5 May 2020 larva; 23 May 2020 em.; Host: Castanopsis sieboldii ; S. Yagi leg.; ELKU. • 1♀; same locality, 3 Jul. 2021, LT; S. Yagi leg.; ELKU. [Kagoshima] • 1♂; Yakushima Is., Hirauti; 19 Sep. 1978; Y. Arita leg.; gen. slide no. KM-329; NSMT. • 1♂; Nakanoshima Is., Mt. Otake; 12 Sep. 2018; K. Sakagami leg.; gen. slide no. KM-330; ELKU. - Ryukyus [Kagoshima] • 1♀; Amamioshima Is., Oosima-gun, Uken-son, Mt. Akatsuchi ; 5 Oct. 2020, LT; J. Oku leg.; ELKU. • 1♂; Tokunoshima Is., Yonama Amagi-cho; 11 Jul. 2016; S. Yagi leg.; gen. slide no. KM-383; ELKU. - [Okinawa] • 1♂; Kunigami district , Oogimi, Oshikawa area ; 27 Mar. 2021, LT; J. Oku leg.; ELKU. • 2♀♀; Ishigakijima Is., Mt. Bannadake ; 4-7 Apr. 2001; T. Ueda leg.; gen. slide no. KM-424; OPU. • 1♀; Iriomotejima Is., Airagawa forest road, Taketomi Yaeyama; 26 Aug. 2020; Y. Hisasue leg.; ELKU .

For the diagnosis of the adult and the detailed description of the adult and genitalia, see Lee et al. (2018).

Description.

Larva (Figs 10G, H , 14 , 15 ). Length 3.5-3.6 mm (n = 2). Head subglobular, yellowish brown with blackish pigmentations on ocellar area and anterior margin of labrum. Body pale yellow in early instars and yellowish brown in late instars. Prothoracic shield yellowish brown, with blackish brown on caudal margin. Thoracic legs short, pale yellow (Fig. 15A ). Pinacula more or less rounded, blackish brown on T1-T3, A1, A2, A8, and A9; paler on the remaining abdominal segments. Anal shield heavily sclerotized, yellowish brown (Figs 14D , 15D ). Anal fork present, deeply emarginated posteriorly, forming two lateral lobes (Figs 14E , 15D ). Anal prolegs armed with many minute spines on dorsal surface. Crochets in a circle, uniordinal, 10-14 in number on ventral prolegs (Fig. 15B ), 6-8 on anal proleg (Fig. 15C ).

Chaetotaxy (Fig. 14 ). Head (Fig. 14A, B ). Epicranial suture shorter than frontoclypeus, AF1 ~ ½ length of AF2; C2 slightly longer than C1; P1 dorsolateral to AF1, ~ 5 × longer than P2; P2 dorsolateral to AF2 and above P1; MD1-MD3 setae forming nearly in a line at the posterior margin of the head capsule, MD1 slightly anteroventral to MD2 and MD3; mouthparts semi-hypognathous; genal area with six stemmata, forming a semicircular pattern; A1 dorsoanterior to stemma-3, slightly shorter than A3; A2 dorsolateral to A1 and shorter than A1 and A3; L1 dorsoposterior to stemma-1; distance between L1 from A3 slightly longer than distance between A3 from A2; S1 below stemma-3, short as A2; S2 longer than S1 and S3, near the opening of the stemmatal semicircle; S3 slightly shorter than S1 and ventroposterior to stemma-6; SS1 near a mandibular condyle, the same length as SS2; SS2 between SS1 and SS3; SS3 ~ 3 × longer than SS1 and SS2; MGa present, close to MG1. Mandible with five teeth (Fig. 14C ).

Thorax. Prothorax (Fig. 14F ): shield with SD1 ventrolateral to XD1 and XD2, all three along anterior margin; XD2 less than 2½ distance from XD1 than from SD1; XD1 ~ 2 × longer than XD2; SD2 and D1 ca. equal in length, both setae ~ 2½-3× length of SD1 and D2; SD2 ca. twice the distance from XD2 than from SD1; L-group tri-setose on the same pinaculum, anteroventral to spiracle; L1 longest; L2 and L3 short, ca. equal in length; SV-group bi-setose on the same pinaculum; SV1 ~ 2- 2½ × longer than SV2; MV1 absent; MV2 approximate to anterolateral coxal margin; V1 approximate mesoposterior coxal margin. Mesothorax and metathorax (Fig. 14F ): D and SD group arranged in a vertical line; D1 and D2 on same pinaculum, D2 ~ 3½-4× length of D1; SD1 and SD2 on the same pinaculum, SD1 ~ 3½-4× length of SD2; MD1 anteroventral to D2; MSD1 in line with MSD2, anterior to SD2; MSD2 anterior to SD1; L-group trisetose; L1 ~ 2½-3× length of L2, each on separate pinaculum; pinaculum of L2 slightly anterior to SD group pinaculum; L3 slightly longer than L2, vertical line with SV1; MV1, MV2, and MV3 anterior to coxa; MV2 near to anterolateral coxal margin, MV3 slightly above V1.

Abdomen (Fig. 14F ). A1 and A2 with D2 ~ 3½-4× longer than D1; D1 dorso-anterior to D2; MD1 slightly ventral to D1 and D2; SD1 ca. equal in length to D2; SD2 minute, anteroventral to SD1; SD1 above spiracle; L-group tri-setose; L1 and L2 on separate pinaculum, L2 in vertical line with SD1 and spiracle; L1 ~ 3½-4× longer than L2 and L3; L3 slightly longer than L2; SV-group bi-setose on A1, SV1 ~ 2½-3× longer than SV2 and on same pinaculum; SV-group tri-setose on A2, with SV1 and SV2 on the same pinaculum, SV3 on separate pinaculum (not shown); MV3 dorso-anterior to V1. A3-A6 as in A2, except D2 dorsoposterior to D1 and SV1-SV3 on separate pinaculum; each segment bearing a pair of protuberant prolegs; planta bearing uni-ordinal, uniserial crochets in a circle (Fig. 15B ). A7 as in A3-A6 except with SV-group bi-setose on same pinaculum. A8 as A7 except: SD1 ~ 1/3 × length of D2 and in vertical line with D2; SD2 remote from spiracle and not vertical to MD1; minute SD2 anteroventral to SD1 and spiracle; SD1 pinaculum slightly anterodorsal to spiracle; spiracle dorsal to all spiracles on A1-A7; L1 ~ 3½-4× length of L2 and below spiracle; L2 and L3 on separate pinaculum; L2 anteroventral to L1 and in vertical line with D2 and SD1; L3 ventral to L2; SV and V group uni-setose. A9 as above except with D1 ventral to D2, D2 ~ 2 × longer than D1; D-group and MD1 on same pinaculum; MD1 in horizontal line with D2; SD1 absent; L-group bi-setose on same pinaculum, L1 ~ 3½-4× longer than L2.

Pupa (Figs 18 , 19 ). Length 3.5-4.2 mm (n = 3). Cylindrical, yellowish brown, dark brown before emergence. Head semi-globular. Vertex with many minute spines. Prothorax with a pair of more or less wedge-shaped projections on the dorsolateral corner of tergite (Fig. 19A, D ). Antennae and forewing reach the midway or near posterior margin of A6. Maxilla (galea) basally broad, gradually narrowing and extending to the posterior margin of A4. Prothoracic legs extending to A2; mesothoracic legs extending to near posterior margin of A4; metathoracic legs extending to midway or near posterior margin of A7. A5-A10 movable. A5 and A6 with a transverse row of tergal spinules directed posteriorly on the anterior margin in males (Fig. 18A, C ) and with a transverse row of dot-like spinules in females (Fig. 18D, F ). A7 with a transverse row of tergal spinules, directed posteriorly on the anterior margin in both males and females (Fig. 18A, D ). Sternite A7 with a pair of oval pads armed with a row of spinules directed anteriorly in females (Fig. 18E ) but absent in males (Fig. 18B ). A10 delineated with a row of short spinules along its outer margin posteriorly in both males and females (Fig. 18C, F ), apically with three pairs of hooked setae on ventral surfaces of A9 and A10.

Distribution.

Japan (Honshu, Kyushu, Ryukyu), China, Taiwan, and India.

Host plant.

Castanopsis cuspidata (Thunb.) Schottky (new host record), C. sieboldii (Makino) Hatus. ex T. Yamaz. et Mashiba (new host record) ( Fagaceae ).

Biology

(Fig. 10 ). We found one preserved specimen of this species with a label noting that it feeds on Castanopsis cuspidata ( Fagaceae ) and a case of the leaf of its host plant. We found that the larvae fed on another host plant, C. sieboldii . In the latter host plant, the larva first makes a small hole (Fig. 10C , red arrow) to enter and feed on the plant tissue in the midrib of the leaf, and this hole also seems to eliminate its feces. After the larva gradually develops by feeding inside the midrib, it leaves the midrib by creating another small exit hole (Fig. 10C , black arrow). After leaving the mine, the larva crawls towards the upper tip of the leaf, cuts transversely from its outer margin to the inner part of the leaf (Fig. 10D, E ), and then makes a shelter with it. The larva usually consumes the leaf by leaning halfway from its shelter. Subsequently, it cuts the leaf around the radius and reaches a small and regular shape to construct a portable case (Fig. 10F, G ). After that, a number of these several small leaf pieces (5-7 pieces, n = 6) were accumulated and stacked into a compact, approximately circular leaf case until the final instar larva (Fig. 10I ). The final larva fixes its case (Fig. 10J ), and pupation occurs inside its case (Fig. 10K ). The adult emerges by leaving the pupal exuvia (Fig. 10L ). The resting posture of the adult is similar to that of the stathmopodid species, keeping its hindlegs upwards (Fig. 9A ). This species overwinters in the adult stage, and adults are collected throughout the year ( Sakamaki 2013).

Remarks.

The larva of P. pylartis was reported as a petiole-miner on the host plant Quercus myrsinaefolia Blume ( Fagaceae ) on Mt. Hikosan, Fukuoka Pref. ( Kuroko 1957). However, we could not find any specimens at ELKU and HBEF that were shown as the depositories in that study, and all specimens collected on Mt. Hikosan in the present study were identified as P. acerosa . Therefore, we conclude that the previous host record of " Thyrsostoma pylartis " reported by Kuroko (1957) was misidentified as P. pylartis because they are very similar to each other in external morphological characters and in the female genitalia.

According to previous records (e.g., Inoue 1954; Moriuti 1982; Sakamaki 2013), P. pylartis is distributed from Honshu to the Ryukyus in Japan. However, P. pylartis is not common in Honshu and Kyushu, whereas P. acerosa is expected in this region. Thus, previous distributional records must be reviewed.

Figures

Figure 1. Adults of Palumbina spp. A P. pylartis, male B ditto, female C P. acerosa, male D ditto, female E P. grandiunca, male F ditto, female. Scale bars: 4.0 mm.

Figure 6. Male genitalia of Palumbina spp. A P. pylartis, genitalia slide no. KM- 383 B P. acerosa, genitalia slide no. KM- 320 C P. grandiunca, genitalia slide no. SY 1454 D P. operaria, genitalia slide no. KM- 389 E P. macrodelta, genitalia slide no. SY 1455 F P. muraseae sp. nov., holotype, genitalia slide no. KM- 374. Scale bars: 0.40 mm.

Figure 7. Abdominal segments of Palumbina spp. A P. pylartis, slide no. KM- 383 B P. acerosa, slide no. KM- 320 C P. grandiunca, slide no. SY 1454 D P. operaria, slide no. KM- 389 E P. macrodelta, slide no. SY 1455 F P. muraseae sp. nov., holotype, slide no. KM- 374. Scale bars: 1.0 mm.

Figure 8. Female genitalia of Palumbina spp. A P. pylartis, genitalia slide no. KM- 330 B P. acerosa, genitalia slide no. KM- 381 C P. grandiunca, genitalia slide no. SY 1453 D P. operaria, genitalia slide no. Palumbina No. 1 E P. macrodelta, genitalia slide no. KM- 328 F P. muraseae sp. nov., whole genitalia, genitalia slide no. KM- 348 and signum, genitalia slide no. KM- 427. Scale bars: 0.50 mm.

Figure 9. Resting position of adult Palumbina spp. A P. pylartis, female B P. acerosa, female C P. grandiunca, female D P. muraseae sp. nov., male.

Figure 10. Palumbina pylartis and its host plant in Fukuoka Pref. A host plant: Castanopsis sieboldii (Fagaceae) B infected leaf C small hole at the base of the midrib of leaf (Upper surface) D leaf tip cut by larva E larva protruding from its leaf shelter F leaf cut by larva G newly leaf case made by larva H, I dried leaf case on upper and lower leaf surface J pupa in a cocoon K pupa L pupal exuvia left by an emerged adult.

Figure 14. Chaetotaxy of P. pylartis. A head, frontal view B ditto, lateral view C mandible D anal plate E anal fork F the prothorax, mesothorax and abdominal segments 1, 6 - 9. Scale bars: 0.10 mm (A, B, F); 0.20 mm (C, D, E).

Figure 15. Larva of P. pylartis. A thoracic leg B crochets C anal proleg D anal shield. Scale bars: 0.40 mm (A, C, D); 0.20 mm (B).

Figure 18. Pupa of P. pylartis. A-C male pupa D-F female pupa A, D dorsal view B, E ventral view and C, F lateral view. A arrows on A 5, A 6 and A 7 indicate a transverse row of tergal spinules anteriorly B and E arrow on A 7 indicates an oval pad without a row of spinules in males and with a row of spinules in females C and F the arrow on the vertex indicates many minute spines, and the arrow on A 10 indicates short spinules D the arrow on A 7 indicates a row of tergal spinules near anterior margin and arrows on A 5 and A 6 indicate a transverse row of dot-like spinules. Scale bars: 1.0 mm.

Figure 19. Pupa of P. pylartis A-C male pupa D-F female pupa A, D ventral view B, E lateral view and C, F dorsal view.