Prochetostoma expandens Sueyoshi & Han

Sueyoshi, Masahiro & Han, Ho-Yeon, 2011, Prochetostoma expandens (Diptera: Tephritidae) sp. n., a fruit parasite of Ilex integra Thunberg (Aquifoliaceae) in Japan, Zootaxa 2784, pp. 39-50 : 40-47

Prochetostoma expandens Sueyoshi & Han , sp. n.

( Figs. 1–8 )

Acidiella sp.: Sasaki et al. 1985: 15.

Gen. sp.: Ichita 1996: 17; Iwase et al. 2000: 375. Prochetostoma sp.: Han 2006: 149.

Genus sp.: Sueyoshi 2000: 438; Sueyoshi 2005a: 306; Sueyoshi 2005b: 334.

Adult (male). Body yellow-brown in ground color, with black setae and setulae ( Fig. 2 a, b). Body length 4.4–6.1 mm (n=8), wing length 4.9–6.2 mm (n=8).

Head ( Fig. 3 a) with frons-head ratio 0.36–0.44, eye ratio 0.56–0.71, gena-eye ratio 0.17–0.24; medial vertical seta 0.61 times as long as longest diameter of eye; lateral vertical seta 0.62 times as long as medial vertical seta; postocellar seta 0.49 times as long as medial vertical seta; paravertical seta 0.56 times as long as postocellar seta; ocellar triangle dark brown; ocellar seta 1.86 times as long as ocellar triangle; frons with sparse, fine, dark brown setulae, 2 pairs of orbital setae; 3 pairs of frontal setae; antenna with arista-antenna ratio 1.33–1.67; scape and pedicel with black setulae; arista dark brown with short pubescence; face ventrally slightly projecting beyond anterior margin of parafacial and facial ridge in profile; parafacial 0.33 times as wide as postpedicel; facial ridge and ventral margin of gena with some short, black setulae; genal seta long and black; postgena slightly swollen, with black setulae; postocular setae extended to half distance from dorsal eye margin to ventral eye margin; proboscis short; palpus with black setulae.

Thorax yellow brown, with black setae and setulae; scutum with dorsoventral seta half distance from level of postsutural supra-alar seta to intra-alar seta; scutellum with anterior setae 2.20 times as long as scutellum, posterior seta 1.80 times as long as scutellum, parallel; proepisternum with long, fine, black setulae; anepisternum with 2 strong setae of similar length; mediotergite shiny yellow brown, with pair of dark brown round markings.

Wing ( Fig. 3 b) with wing-thorax ratio 2.38–2.68, vein R4+5 ratio 1.66–1.88, vein M ratio 0.45–0.61, subcostalcostal ratio 0.31–0.40; vein R4+5 with 9 tiny setulae between node and crossvein r-m, 2 setulae beyond crossvein rm; wing markings pale brown to dark brown; discal marking ( Fig. 3 b: A) united to short brown marking ( Fig. 3 b: B) extending from costa to crossvein r-m, at cell br, extending to posterior margin of wing, forming transverse marking; apical C-shaped band marking ( Fig. 3 b: C) expanding at apex to fill apex of cell r4+5; transverse marking separate from apical C-shaped band marking at posterior margin of wing.

Legs entirely yellow brown, with black setae and setulae; fore femur with 7 or 8 long posteroventral setae.

Abdomen slightly wider than long in dry specimen; shiny yellow brown with black setae and setulae; each of T3–5 with black round markings laterally; epandrium ( Fig. 3 c, d) yellow brown, with black setae; surstylus apically truncated in lateral view; bacilliform sclerite with 2 prensisetae; medial prensiseta much larger than lateral prensiseta; phallapodeme slender rod-like in shape; glans of distiphallus ( Fig. 4 a, b) with apicodorsal rod, without median sclerite; dorsal sclerite with pattern of approximated fusiform cells at basal portion and hexagonal cells at apical portion; each hexagonal cell with some tinny granules ( Fig. 4 b).

Female (body length 4.9–6.3 mm, n=12; wing length 5.3–5.9 mm, n=11) is similar to the male but differing as the follows: T6 with pair of black markings; syntergosternum 7 ( Fig. 3 e, f) yellow brown, with fine dark brown setulae, apex with 4 long setae each on dorsal and ventral margin; eversible membrane covered with teeth-like processes similar in size; taeniae extending length of eversible membrane; aculeus ( Fig. 4 c) long, parallel-sided, apical 1/4 tapered to apex; 3 globular spermathecae ( Fig. 4 d), dark brown, with transverse spinular patterns; 1 spermatheca smaller than other 2; duct of smaller spermatheca more swollen than those of other 2 spermathecae.

Third instar larva. Body length 3.3–4.2 mm; width 0.9–1.2 mm (based on 7 specimens from Urawa C, Saitama P); body cylindrical and tapered to cephalic segment, posterior apex truncate; body entirely creamy whitish ( Fig. 5 a).

Cephalic segment: cephalic lobe covered with reticulate rugose pads, containing dorsal, terminal and stomal organs ( Fig. 6 a). Dorsal organ dorsal to terminal organ, containing hemispherical dome ( Fig. 6 b); terminal organ consisting of distal group and dorsolateral group; distal group with three papilla sensilla and two knob sensilla; dorsolateral group only with modified papilla sensilla; ventral organ ventral to terminal organ, containing hemispherical dome and pit sensilla. Oral ridge with serrate margin ( Fig. 6 a,b).

Mandible black and well sclerotized, apex round, without accessory teeth ( Fig. 3 g); mandibular hook pointed and strongly curved downward, ventral margin undulate on basal part, dorsal projection slender and pointed, connected to abductor apodeme ( Fig. 3 g); ventral margin of mandible abrupt, connected to adductor apodeme ( Fig. 3 g); median oral lobe transparent on basal portion, darkened with black apical portion. Labial sclerite black, well sclerotized and developed, Y-shaped in ventral view, with divergent posterior projection ( Fig. 3 h). Hypopharyngeal sclerite black, well sclerotized on anterior half, loosely fused with pharyngeal sclerite, with weakly sclerotized ventral bridge medioventrally and posterior process on posterior angle ( Fig. 5 b); parastomal bar very short. Pharyngeal sclerite ( Fig. 5 b): paraclypeal phragma dark brown to black, well sclerotized; clypeal sclerite and prothoracic phragma transparent and weakly sclerotized; anterior sclerite short and weakly sclerotized; dorsal cornu longer than ventral cornu, ventral cornu with window; pharyngeal phragma transparent, weakly screlotized, expanded laterally; ventral pharyngeal ridges indistinct.

T1 without spinules. Anterior spiracle situated near posterior margin of T1, projected perpendicularly to body surface, with 19 tubules arranged dorsoventrally in 2 rows, apex of each tubule rounded, with slit-like opening; felt chamber globular, without reticulation ( Fig. 6 c). T2 and T3 each with spinulose belt encircling anterior margin; spinules slightly compressed, all directed posteriorly, about 10µm in length, irregularly arranged in 6 or 7 rows dorsally and 2 or 3 rows laterally; lateral spiracular complex consisting of spiracular opening situated near anterior margin of each segment and 3 pit sensilla posterior to opening ( Fig. 6 d).

A1–7 each with intrasegmental fold on ventral side, with spinulose belt encircling anterior margin of each segment; spinules of belt arranged in irregular rows, directed posteriorly; lateral spiracular complex consisting of spiracular opening near anterior margin of each segment and 3 pit sensilla posterior to opening. Caudal segment with intrasegmental fold on ventral side, spinules present only on ventral side, with longitudinal anal slit opening on ventral side of posterior intrasegment; anal lobes distinct, with distinct spinules along posterior margin ( Fig. 7 d). Sensilla of caudal segment ( Fig. 7 a): 2 pair of dorsal tubercles, each with papilla sensillum; intermediate tubercles containing lateral and medial tubercles, medial intermediate tubercles subdivided into medial and lateral lobes, medial lobe with bifid stelex sensillum, lateral lobe with papilla sensillum ( Fig. 7 b), lateral intermediate tubercle with pit sensillum; 2 lateral tubercle with papilla sensillum; ventral tubercle with pit sensillum. Spiracular plate situated on dorsal half of spiracular area, directed obliquely upward ( Fig. 7 d); 3 spiracular openings arranged in parallel to each other, each opening 2 times as long as wide, rimae well elevated entirely ( Fig. 7 c); 4 interspiracular processes white or transparent, well developed, arranged outside of spiracular openings, fan-like with 16–19 developed cuneiform branches each bearing 1–3 pointed serration at apex; ecdysical scar situated on medial lateral side of spiracular openings ( Fig. 7 c).

Specimens examined. Adults. Holotype (3): “[ Japan: Honshu]/ Imperial Palace/ Naka-Dokanbori/ Tokyo/ 18.IV.1997 / S. Nomura”, “Pc.1008” (NSM). Paratypes, 25322Ƥ – [HONSHU] Chiba P: Matsudo C, Matudo, 433Ƥ, 19.iv.2002, 2Ƥ, 16.v.2003, 1Ƥ, 23.v.2003, 1Ƥ, 30.v.2003, (Pc. 2001–2011) (FFPRI); Shirako T, 43, 30.iv.2001 (Pc.2012) (FFPRI). Saitama P: Urawa C, Negishi, 134Ƥ (reared specimens) (Pc. 1009–1012) (BLKU). Tokyo Metropolis: Hachijo Is., Uramigataki, 1Ƥ, 1.v.1997 (Pc.1022) (BLKU); Hachijo Is., Botanical Gardens, 13, 2.v.1997 (Pc.1023, 1039) (BLKU); Imperial Palace, 1Ƥ, 18.iv.1996, 13, 24.iv.1996, 13, 14.v.1996, 13, 20.v.1996, 1Ƥ, 18.iv.1997, 1Ƥ, 23.iv.1998, 1Ƥ, 18.iv.2000, 23, 14.v.2001 (Pc. 1001–1007, 1031, 1032) (NSM); Tokiwamatsu, 1Ƥ, 22.iv.2003, 131Ƥ, 13.v.2003 (Pc. 1033–1035) (NSM). Kanagawa P: Yokohama C, Nokendaimori, 1Ƥ, 31.iii.1997, 1Ψ, 26.iv.1997, 33, 3.iv.1998, 13, 10.iv.1998 (Pc. 1013–1018) (BLKU); Miura C, Bishamon, 331Ƥ, 8.iv.2001 (Pc. 1027–1030) (BLKU); Chigasaki C, Tsutsumi, 1Ƥ, 26.iv.1999 (Pc.1020) (BLKU); Ebina C, Otani, 13, 7.iv.2000 (Pc.1019) (BLKU). Yamaguchi Pref.: Nagato C, Omi Is., 13, 11.iv.1992 (Pc.1021) (BLKU). Other specimens: [HONSHU] Chiba P: Matsudo C, Matsudo, 132Ƥ, 2.v. 2003, 13, 9.v.2003 (Pc. 2013–2017) (FFPRI). Kanagawa P: Miura C, Bishamon, 131Ƥ, 13.iv.2001, 13, 19.iii.2002 (Pc. 1036-1038) (BLKU). [SHIKOKU] Tokushima P: Yuki T, Kiki, 231Ƥ (reared specimens) (Pc. 1024–1026) (KPPS), 13 (reared specimens), 22.xii.1978 (Pc.3001).

Larvae and prepupae. [HONSHU] Chiba P: Matsudo C, Matsudo, 5 larvae, 23.v.2003; 3 larvae, 6.vi.2003; 2 larvae, 4.vii.2003; 1 larvae, 18.vii.2003; 3 larvae, 31.vii.2003; 5 larvae, 17.viii.2003; 4 larvae, 29.viii.2003; 2 larvae, 11.ix.2003; 4 larvae, 26.ix.2003; 4 larvae, 26.ix.2003; 6 larvae, 10.x.2003; 6 larvae, 24.x.2003; 4 larvae from fruits pruned from tree, 5 larvae from fruits dropped on ground, 7.xi.2003; 2 larvae, 21.xi.2003; 6 larvae, 2 prepupae, 5.xii.2003; 2 larvae, 19.xii. 2003.

Etymology. The specific epithet is derived from the anterior apical wing band broadened at apex.

Parasitoid. 134Ƥ of Opius sp. ( Hymenoptera : Braconidae ) were reared from puparia collected at Urawa, Saitama.

Host plant. Ilex integra Thunberg. Sasaki et al. (1985) reported this species (as Acidiella sp.) as a fruit feeder on Ilex integra . This relationship was confirmed in the present study.

Distribution. Japan (Honshu, Shikoku, Hachijo Island) ( Fig. 1 ).

Figures

FIGURE 1. Distribution map of Prochetostoma expandens. Arrow indicates the locality of the study site for investigation of life history.

FIGURE 2. Habitus of Prochetostoma expandens. a, b, male; c, d, female. a, c, left lateral view; b, d, dorsal view.

FIGURE 3. Prochetostoma expandens. a, Head, left lateral view; b, right wing in dorsal view; c, d, male epandrial complex (epandrium, surstylus, and proctiger). c, left lateral view; d, posterior view. e, f, female syntergosternum 7 and 8 th abdominal segment. e, dorsal view; f, ventral view. g, h, cepharopharyngeal structure. g, left mandible, lef lateral view; h, labial sclerite, ventral view. a – d, Holotype; e, f, paratype (Pc. 1007); g, h, Pc. 3 L 02. Scale bars: a, c, d, 1 mm; e, f, 0.5 mm; g, 0.2 mm; h, 0.1 mm. Abbreviations: A, discal marking; B, short brown marking; C, apical C-shaped marking; em, eversible membrane; ep, epandrium; ps, prensiseta; s, sursylus; t, taeniae; 7 ST, syntergosternum 7.

FIGURE 4. Postabdominal structure of Prochetostoma expandens. a, b, Phallus (holotype). a, right lateral view; b, hexagonal cells of acrophallus. c, aculeus, dorsal view (Pc. 1007). d, spermathecae.

FIGURE 5. Third instar larva of Prochetostoma expandens (Pc. 3 L 02). a, Body, left lateral view; b, cephalopharyngeal skeleton, left lateral view.

FIGURE 6. Third instar larva of Prochetostoma expandens (Pc. 3 L 01). a, Cephalic segment, anterolateral view; b, sensory organs on left cephalic lobe, anterior view; c, left anterior spiracle, dorsal view; d, left lateral spinules on anterior margin of T 1. Abbreviations. d, hemispherical dome of cephalic lobe; k 1 – 2, knob sensilla; m, modified papilla sensillum; p, papilla sensillum of dorsolateral group; p 1 – 3, papilla sensilla of distal group.

FIGURE 7. Third instar larva of Prochetostoma expandens (Pc. 3 L 01). a, caudal segment, posterior view; b, medial intermediate tubercle of caudal segment; c, left spiracular plate, posterior view; d, anal lobe, ventral view. Abbreviations. dt, dorsal tubercle; e, ecdysial scar; i, interspiracular process; lt, lateral tubercle; lit, lateral intermediate tubercle; mit, medial intermediate tubercle; s, stelex sensillum of medial lobe; p, papillar sesillum of lateral lobe.

FIGURE 8. Fruits of Ilex integra, infested by larvae of Prochetostoma expandens. a, A fresh fruit with infestation; b, a first instar larva burrowing under the skin of fruit; c, second instar larva burrowing wall tissues among seeds; d, mature third instar larva and heavily infested fruit.