Bucculatrix flavimaculata Yagi & Hirowatari, 2024

Yagi, Sadahisa, Oku, Johei & Hirowatari, Toshiya, 2024, A new Hibiscus - feeding species of Bucculatrix (Bucculatricidae) from the Ogasawara Islands, Japan, Nota Lepidopterologica 47, pp. 29-42 : 29

Bucculatrix flavimaculata Yagi & Hirowatari sp. nov.

Diagnosis.

This species can be easily distinguished from other Bucculatrix species distributed in the surrounding biogeographic regions by its fuscous forewings mixed with four yellowish cream marking at or near costal margin. The male genitalia are similar to those of B. firmianella (Group 1 sensu Kobayashi et al. 2010) in that they share a long and slender socius, a broad valva, and an elongated vinculum. Moreover, they also share an elongated ductus bursae in the female genitalia. However, this species can be distinguished by the trapezoid valva (triangular in B. firmianella ) and small-scale sac (large in B. firmianella ) in males and the broad lamella antevaginalis with some wrinkles in females (without wrinkles in B. firmianella ).

The male and female genitalia are also similar to those of Bucculatrix serratella Kobayashi et al., 2010 (Groups 8 sensu Kobayashi et al. 2010), which share a long and slender socius and rounded apex of the valva in the male genitalia. They also share the lamella antevaginalis with wrinkles in the female genitalia. However, the species can be distinguished by the absence of a juxta in the male genitalia and long ductus bursae (short in B. serratella ) in the female genitalia.

Description.

Adult (Figs 1 , 2 ). No sexual dimorphism. Wingspan 3.8-6.6 mm (n = 16; holotype: 6.6 mm). Forewing length 1.7-3.0 mm (n = 16, holotype 3.0 mm).

Head: Frons pale dark brown with cream scales, apically cream. Vertex cream with dark brown hair-like scales. Antennae filiform, 4/5 of forewing length; scape cream, forming eye-caps with cream hair-like scales ventrally; pedicel cream with dark greyish-brown scales; flagellum dark greyish-brown. Proboscis yellowish cream without scales. Labial palpus short, cream.

Thorax: Fuscous with cream scales dorsally, dark greyish-brown laterally. Forecoxa to forefemur cream; fore tibia greyish-brown dorsally, yellowish-cream ventrally; fore tarsomere yellowish-cream basally and ventrally, greyish-brown dorso-apically; mid-coxa to mid-femur cream; mid-tibia greyish-brown with yellowish cream marking middle dorsally; mid-tarsomere yellowish cream basally and ventrally, greyish-brown dorso-apically; hind coxa to hind femur cream. hind tibia greyish-brown with long hairs dorsally, yellowish cream with long hairs ventrally; hind-tarsomere yellowish cream basally and ventrally, greyish-brown dorso-apically. Forewing lanceolate, ground colour fuscous with four inconspicuous cream to dark yellow spots or markings on basally, 1/4, 1/2, 3/4 of forewing; basal marking slender strip, not reaching inner margin; marking at 1/4 divided into two or three spots at middle of forewing; spot at 1/2 at costal margin; marking at 3/4 divided into two spots at costal margin and tornus, tornus spot larger than costal spot; black erected spot at basal 2/5 of forewing near inner margin (Figs 23 , 24 ); fringe dark greyish-brown. Hindwing greyish-brown; fringe greyish-brown.

Abdomen: Greyish-brown dorsally, cream ventrally. Scale sac small, ovate.

Male genitalia (Figs 3-9 ): Uncus and gnathos absent. Socius elongated, apical half with setae, apex slightly broad. Tegumen narrow with one pair of small lobes with setae laterally. Vinculum developed and elongated with a broadly roundish tip. Valva trapezoid, apex slightly broad and roundish. Anellus membranous covered with minute sclerites (Fig. 8 ). Phallus elongated, J-shaped, tapered toward tip, slightly curved and crinkled posteriorly; with a U-shaped lobe basally.

Female genitalia (Figs 10-12 ). Papilla analis moderately long, tapering toward the tip. Apophysis posterioris slender, longer than eighth segment. Apophysis anterioris absent. Ostium bursae broad. Lamella antevaginalis broad with several horizontal wrinkles. Antrum elongated, bar-shaped, and slightly shorter than posterior apophysis. Ductus bursae narrow and elongated, longer than corpus bursae. Corpus bursae anteriorly broad, posteriorly tapering toward ductus bursae, with significant signa. Signa arranged in two rows; each signum forming posterior row with sharp internal spine; that of anterior row with blunt internal process. Ductus seminalis slender, arising near border of ductus bursae and corpus bursae.

Type material.

Holotype. ♂; '[JPN: Ogasawara Isls.] Higashidaira, Chichijima Is., Ogasawara-mura; 18.vi.2022 larva; S. Yagi leg.', 'M2808; Host: Hibiscus glaber ; 4.vii.2022 em.', genitalia slide no. SY1459(♂); Sample ID for DNA analysis: SaY892; Collection ID: ELKU-I-L-Bonin 0000155; deposited in ELKU.

Paratypes. [Chichijima Is.] • 1♂; same locality and collector; 26.vi.2022 Sweeping; genitalia slide no./Sample ID: SY1457(♂)/Jo000031; ELKU. [Hahajima Is.] • 6♂7♀; Ogasawara-mura, Hahajima Is., Igumadani; 22.vi.2022; Host: Hibiscus glaber ; 2-6.vii.2022 em.; S. Yagi leg.; genitalia slide no./Sample ID: SY1307(♂)/SaY737, SY1446(♀)/SaY887, SY1447(♀)/SaY888, Bonin000032(♂)/Jo000032, Bonin000033(♂)/Jo000033; ELKU • 1♂1♀; Ogasawara-mura, Hahajima Is., Chibusayama; 21.vi.2022 larva; Host: Hibiscus glaber ; 2-4.vii.2022 em.; S. Yagi leg.; genitalia slide no./Sample ID: SY1458/Jo000030; ELKU.

Host plant.

Hibiscus glaber (Matsum. ex Hatt.) Matsum. ex Nakai ( Malvaceae ).

Biology

(Figs 13 - 24 ). Eggs were mainly deposited on the upper side (n = 10) and sometimes on the underside of the leaf (n = 2), near a leaf vein or leaf edge. The young larvae are leaf miners. Leaf mining usually starts as a serpentine mine and changes to a simple linear mine. Subsequently, the larvae exit the mine, feed on the upperside or underside of the leaf, and leave the typical Bucculatrix “skeletonized” feeding trace after only the epidermis is consumed and veins remain. The cocoonet is typically located on the underside of the leaf. All larvae of the discovered species are pale green, except for the last instar. The last instar larva has dorsal fuscous and cream horizontal stripes and two lateral white markings on each segment. The spindle-ribbed cocoon is pale cream at first, and then cream. Adults and larvae were observed at almost the same time from mid-June to late June. Our collections demonstrate that this species may be multivoltine.

Distribution

(Fig. 25 ). Japan: Ogasawara Islands (Chichijima, Anijima, Hahajima, and Mukohjima Islands). Adults were collected from Chichijima and Hahajima Islands. However, many feeding traces on the same host that we presume are from the newly described species were observed on Anijima and Mukohjima Islands (Figs 14 , 25 ).

DNA data

(Figs 26 , 27 , Suppl. material 2). The DNA barcode sequences are deposited into the GenBank database under the accession numbers listed in Table 1 and uploaded to the BOLD system in the public dataset DS-BUCBONIN. The intraspecific p-distances of B. flavimaculata sp. nov. are 0-2.74% (n = 6) (Suppl. material 2). The largest p-distances were found between two specimens collected from Chichijima Island (BIN, BOLD:AFB6292) compared to six Hahajima Island specimens (BIN, BOLD:AFB5723) (2.43-2.74% pairwise distances) (Fig. 26 , Suppl. material 2).

The DNA barcode of B. flavimaculata sp. nov. (Sample ID: SaY892) is closest to that of a Bucculatricidae species collected in Selangor, the peninsula of Malaysia (BIN, BOLD:ACR3285, Sample ID: BIOUG17088-B08, Process ID: GMMGT2203-14), based on the BOLD identification engine, with 6.46% pairwise divergence.

According to the phylogenetic tree constructed based on the COI barcode region, Bucculatrix flavimaculata is closely related to B. firmianella , although the ultra-fast bootstrap support and SH-aLRT support values are low or unsupported (86% and 24.2% respectively) (Fig. 27 ). Moreover, B. flavimaculata and B. firmianella form a clade with two unidentified species from Malaysia, B. hamaboella , B. regaella Chrétien, 1907 ( Malvaceae feeder), and B. cordiaella Davis & Landry, 2002 ( Boraginaceae feeder) with high SH-aLRT support (97.1%, Fig. 27 ).

Etymology.

The name of the new species is derived from the Latin flavus, “yellowish” and macula, “spots”, referring to the colour of the forewing and the spot markings.

Remarks.

In Japan, Bucculatrix hamaboella is known to feed on Hibiscus hamabo Siebold et Zucc. ( Kobayashi et al. 2009). However, its morphological and molecular characteristics are markedly different from B. flavimaculata . Thus, it does not seem to be a closely related species. The young larva of B. hamaboella is a leaf miner that forms a long red linear mine. In later instars, the larva becomes a stem borer ( Kobayashi et al. 2009).

Figures

Figure 25. Distribution map of Bucculatrix flavimaculata sp. nov.

Figure 26. Neighbor Joining tree of the genus Bucculatrix flavimaculata sp. nov. based on the DNA barcode region. The labels provide data on Sample ID, specific name, island, and exact sites. Branch lengths are proportional to genetic distances and the scale bar indicates 0.005 substitutions / site. Within sample names, species names and BIN IDs are followed by sample IDs.

Figure 27. ML tree of the genus Bucculatrix based on the DNA barcode region generated by IQ-TREE web server. Numbers near each node are SH-aLRT support (%) / ultrafast bootstrap support (%). Numbers are indicated in case both support values are higher than 50 (%) / 50 (%). Light blue highlights indicate the species known to feed Malvaceae. Branch lengths are proportional to genetic distances and the scale bar indicated 0.03 substitutions / site.

Figures 1, 2. Adults of Bucculatrix flavimaculata sp. nov. from the Ogasawara Islands. 1. Male, holotype; 2. Female, paratype, genitalia slide no. SY 1446. Scale bars: 3.0 mm.

Figures 19 - 24. Biology and habitat of Bucculatrix flavimaculata sp. nov. (continued) 19, 20. Last instar larva; 21. Cocoon; 22. Cocoon with pupal exuviae; 23, 24. Adult.

Figures 3 - 9. Male genitalia of Bucculatrix flavimaculata sp. nov. 3. Holotype, genitalia slide no. SY 1459; 4, 5, 8, 9. Paratype, genitalia slide no. Bonin 000032; 6, 7. Paratype, genitalia slide no. SY 1457; 3, 4. Whole genitalia, lateral view; 5. Whole genitalia, dorsal view; 6. Genitalia except phallus and left valva, ventral view; 7. Phallus; 8. Anellus, ventral view; 9. Scale sac. Scale bars: 300 μm (3, 4, 5, 6, 7, 9); 100 μm (8).

Figures 10 - 12. Female genitalia of Bucculatrix flavimaculata sp. nov., paratype. 10. Whole genitalia, ventral view, genitalia slide no. SY 1446; 11. Terminal segment, genitalia slide no. SY 1447; 12. Signum, genitalia slide no. SY 1447. Scale bars: 500 μm (10); 200 μm (11, 12).

Figures 13 - 18. Biology and habitat of Bucculatrix flavimaculata sp. nov. Biology and habitat of Bucculatrix flavimaculata sp. nov. 13. Host plant, Hibiscus glaber at Chibusayama, Hahajima Is.; 14. Leaf with mines and traces of feeding at Mukohjima Is.; 15. Leaf with mines and traces of feeding at Igumadani, Hahajima Is.; 16. Mine; 17. Larva; 18. Last instar larva with cocoonet.