Tonza citrorrhoa Meyrick, 1905

Figs 1–13

Tonza citrorrhoa Meyrick, 1905: 614 – Heppner (1992: 74) (species list) – Kobayashi et al. (2015: 69–72, figs 1–2).

Diagnosis

See Kobayashi et al. (2015: 69) and diagnosis of the family.

Material examined (4 ³³, 7 ♀♀, 10 unsexed)

JAPAN:2³³, 5♀♀ adults, Ryukyus, Okinawa Prefecture,Mt.Kubura-dake,Yonaguni Is., 3–6May2016, M. Kimura leg. (host: Putranjiva matsumurae), 22 Apr. 2016 (larva) (OPU-IN-LE 2018IV 0003–0009); material in NHMUK, see above, has not been critically re-examined; 2 ³³, 2 ♀♀, 3 unsexed, pupae, same data as for preceding, but May 2016 (OPU-IN-LE 2018IV 0018–0022); 7 unsexed larvae, same data as for preceding, but May 2016 (OPU-IN-LE 2018IV 0026–0028|SK600, 0025|SK603, 0026|SK604, 0035|SK543(exuvia)).

Type locality

SRI LANKA: Hantane.

DNA barcodes

GenBank accession no. LC 310893, voucher no. SK-097. BIN: BOLD:ACX8102, voucher no. USNMENT00657266.

Additional description

ADULT. Wingspan range 11.0– 14.4 mm (mean 13.7 mm, n = 9): forewing length range 5.2–7.1 mm (mean 6.6 mm, n = 9).

MALE GENITALIA AND FEMALE GENITALIA. See Kobayashi et al. (2015: fig. 2).

MATURE LARVA (FIGS 4–6, 9). Range: 11.5–12.5 mm in length (mean 12.0 mm, n = 4). Integument varying from yellowish green to yellow in colouration, full mature larva yellow in colouration, marked with numerous purple blotches and white dots (Fig. 4). Pinacula conspicuous, dark brown in colouration (Fig. 4A, J). Primary setae long and secondary setae absent (Fig. 4 A–E).

HEAD (FIG. 5). Hypognathous. Head capsule marked with numerous ochreous spots (Fig. 5A, C), 0.90– 1.00 mm in width (mean 0.94 mm, n = 5). Frontclypeus wide, extending a half to epicranial notch. Mandible about 0.15 mm in length, with three large teeth, two smaller teeth, and three small teeth at inner portion, with M 1 and M 2 setae much shorter (Fig. 5F). Six stemmata arranged in an arc except for S 1 and S 6; S 1 more posterior and S 6 ventrad (Fig. 5 A–C).

CRANIAL SETAE (FIG. 5 A–C). MD 1 very long; A 1, A 2 and A 3 as obtuse triangle with A 2 most distant from stemmata; P 1 below Af2– P 2 line; pore not found.

THORAX (FIG. 6 A–B). T 1 shield indistinct, yellow in colouration, marked with dark brown patches. Jugular gland (adenosma) absent, but like structure present ventrally on T 1 (Fig. 4F), anterior to the legs and antero-medial to the long setae SV 1 and SV 2; the structure not eversible and a tubular or sacciform gland at inner side of body not found. D1 and D2 approximated on T 2 and T 3; SD 1 and SD 2 approximated on T 2 and T 3; L-group trisetose, L 1 and L 2 on the same pinacula on T 1 and separated on T 2 and T 3; SV 1 and SV 2 on the same pinacula on T 1 and on separate pinacula on T 2 and T 3; Seta V 1 present on T 1, absent T 2 and T 3. Thoracic legs pale ochreous to brown in colouration; pale brown claws elongate, slightly curved to inner side (Figs 4F, 6B).

ABDOMEN (FIG. 6 C–F). D1 above level of D2 except for A 9; SD 2 very small, separated from pinaculum of SD 1; L-group trisetose on A 1–7, bisetose on A 8 and unisetose on A 9; L 2 minute; SV-group trisetose on A 3 and A 4, bisetose on A 5 and A 6, unisetose on A 1, A 2, and A 7– A 9; Seta D1 of A 9 segment markedly more slender than D2. Anal shield indistinct as in figure 6 F. Prolegs present on A 3, A 4, and A 10 (Fig. 4A, G). Ventral prolegs elongate, about 2× length of width of proleg base; crochets uniordinal, arranged in a circle, being usually 12 in number (Figs 4 H–I, 9L–N). Crochets of the anal prolegs arranged in a semicircle (Fig. 4K).

PUPA (FIGS 7, 10–12). General: long and slender, yellowish green in colouration, 10–11 mm in length, 1.0–2.0 mm in diameter. Maxillary palpi concealed (Fig. 10E). Dorsum of A 2– A 9 with two pairs of minute spiny setae from dorsal side (Figs 7B, C, 11). Other characters as for family diagnosis.

Distribution

INDIA: Khasia/Khasi Hills; Darmsala, Punjab; Coimbatore (NHMUK): new record. SRI LANKA: Colombo, Kandy, Bogawantalawa, Puttalam, Maskeliya, Bentota, Gulla, Dondanduwa, Hikkaduwa, Nawalatipiya (NHMUK): new record, Hantane [Hanthana] (Meyrick 1905). CHINA: Taiwan (Heppner 1992; USNM, on BOLD). JAPAN: Kagoshima Prefecture: Amai-Ohshima Is. (Seino 2016), Okinawa Pref.: Okinawa Is. (Kobayashi et al. 2015), Iriomote Is. (Umetsu 2016), Yonaguni Is.: [new record]. INDONESIA: Telawa, Java (NHMUK; abdomen missing, identity not certain but included among 13 identified specimens constituting Meyrick’s collection); Sulawesi (NHMUK), identity not certain. PHILIPPINES (NHMUK): identity not certain.

Hostplants

Putranjivaceae: Putranjiva matsumurae: new larval hostplant record. The adult has been recorded feeding on ‘Marygold flowers’ [sic; Tagetes L., Asteraceae Bercht. & J. Presl] at Coimbatore, S. India (NHMUK).

Life history

The detailed biology of this species is unknown. The third author (Kimura) observed a number of late instar larvae on the young leaves of Putranjiva matsumurae . The larva is a leaf webber tying together several leaves loosely with silk threads (Fig. 3 A–C). The full grown larva is suspended from the tree by a silk lifeline spun out from the head spinnerets. Pupation takes place at the intersection of some cross silken threads (Fig. 3H). A number of the mature larvae occurred on tall trees of the hostplant in Yonaguni Is., Okinawa Pref. (Fig. 3A). Young larvae were not found in our study. Given that no larval mine was observed, the young larvae are probably external feeders like the later instars.

Remarks

The resting posture of the adult moth with head end lowered and abdomen lifted is similar to certain Argyresthiidae, Ypsolophidae and several genera in Yponomeutidae (Fig. 1B). However, when at repose in nature the suspension may be different and rather unusual involving only the prothoracic and mesothoracic legs in contact with the lower surface of a leaf with the wing and body tending to hang vertically below a leaf. In this position, the antennae relatively long with respect to wing length may accentuate a potential false head-like appearance.

Leaf webbing larvae occur in several yponomeutoid families, Yponomeutidae, Scythropiidae, Plutellidae, Ypsolophidae (Ypsolophinae) and Attevidae (Sohn et al. 2013) . However, larvae of Tonza form rather looser webs than other yponomeutoid leaf-webbers. We observed that the larvae move on silk threads using the claws of the thoracic legs and the prolegs, but cannot move on flat surfaces without silk.

ADULT Male genitalia

Molecular analysis

The COI DNA barcoding region (COI-5P) was sequenced from a Japanese specimen of Tonza . We performed sequence comparison to check species variation for T.citrorrhoa, using the BOLD Identification System (IDS) from the BOLD website (http://www.barcodinglife.org/) [accessed 1 Jul. 2016]. The DNA barcode sequence of T. citrorrhoa (Fig. 2, sample ID: SK-97) was clearly distinguished from that of T. purella registered in BOLD with more than 3% pairwise divergence (Fig. 2) and to a sample from Madagascar belonging to BIN BOLD:ACU1104 by 2.91% pairwise divergence. The nearest neighbour of T. citrorrhoa in the BOLD database which is 0.35% pairwise divergent is a Taiwanese conspecific specimen (Fig. 2), which belongs to the same BIN (BOLD:ACX8102).

Figure 13 shows a maximum likelihood tree of the DNA barcoding region from 23 species of Yponomeutoidea and Gracillarioidea Stainton, 1854, including our sequence, SK-97. This tree based on a single locus could not resolve all the higher-level relationships within the groups, except for Attevidae Mosher, 1916 (85% bootstrapping support). The traditional sense of Plutellidae, which would comprise Plutella Schrank, 1802, Orthenches Meyrick, 1885, and Tonza, among other taxa not represented here, did not form a monophyletic group. Two species, T. citrorrhoa and Glyphipterix equitella Scopoli, 1763, were grouped together with 87% bootstrapping support.