The external male genitalia of the Reduviidae (Hemiptera: Heteroptera)

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1 植物保護學會會刊 45: , The external male genitalia of the Reduviidae (Hemiptera: Heteroptera) Chung-Tu Yang Department of Entomology, National Chung Hsing University, Taichung, Taiwan 402, ROC. (Accepted for publication: Apr. 17, 2003) ABSTRACT Yang, C. T The external male genitalia of Reduviidae (Hemiptera: Heteroptera). Plant Prot. Bull. 45: Neocentrocnemis formosana Matsumura, Isyndus obscurus Dall, Triatoma rubrofasciata De Geer, Oncocephalus sp., and Epidaus sp. were selected for study. Their external male genitalia are described and illustrated. In N. formosana, the external male genitalia do not differ in any significant way from those of other heteropterans. In the latter 4, the ejaculatory duct runs outside of or not runs into the phallobasal conjunctival cavity. In the latter 3, the phallobasal conjunctiva connects to the aedeagus at its longitudinal ventral margin. In the last 2, the phallobasal conjunctival cavity plays the role of the ejaculatory duct. (Key words: Reduviidae, morphology, external male genitalia) INTRODUCTION The external male genitalia of the Reduviidae are the most difficult to understand among the Heteroptera. The chief difficulty is the incredible diversity of the phallobasal conjunctiva. To investigate the morphology of the external male genitalia of the Reduviidae, the author examined 46 species of reduviids. Based on this work, the true features seemingly emerged. The phallobasal conjunctiva connecting to the aedeagus at its longitudinal ventral margin and the ejaculatory duct running outside of the phallobasal conjunctival cavity may like abnormal features but could be true. Results on 5 species, belonging to 5 different

2 128 植物保護學會會刊第 45 卷第 2 期 2003 genera, that more typically represent the morphological variation of male genitalia were selected and are used herein to explain the author s interpretation of the morphology of the external male genitalia of the Reduviidae. Fig. 1. Neocentrocnemis formosana Mastsumura. (A) Abdominal segments IX-XI and genital styles, dorsal view; (B) the same, lateral view; (C) right genital style, dorsal view; (D) genital plates; anterodorsal view; (E) phallus, lateral view; (F) apex of phallus, morphological dorsal view; (G) base of phallus, lateral view. IX, X, and XI refer to abdominal segments IX, X, and XI; aed, aedeagus; cap, capitate processes; con, connective; ejd, ejaculatory duct; gp, genital plates; gs, genital styles; phb, phallobase; phc, phallobasal conjunctiva; phcp, phallobasal conjunctival processes; sub, support bridge; sut, support tube.

3 The external male genitalia of the Reduviidae (Hemiptera: Heteroptera) 129 MATERIALS AND METHODS Neocentrocnemis formosana Matstumura, Isyndus obscurus Dall, Triotoma rubrofastiata De Geer, Oncocephalus sp., and Epidaus sp. were selected for study. Abdominal segments I-XI were placed in a 10% solution of KOH until the organs were transparent, and then put directly into glycerin on cavity slide glass. Specimens were supported by cotton fibers in glycerin. Figures were drawn using a drawing tube. RESULTS Neocentrocnemis formosana Matsumura (Fig. 1) Abdominal segment IX subquadrate in dorsal view, with dorsomedial portion membranous (Fig. 1A), anterior opening directed anterodorsad (Fig. 1B). Abdominal segment X slender. Abdominal segment IX retracted into segment X. Genital styles symmetrical in size and shape, apical 1/3 directed mesad (Fig. 1A, C). Genital plates arch-shaped in anterodorsal view (Fig. 1D). Phallus directed caudad within segment IX (Fig. 1B, E). Connective relatively small. Support bridge with upper portion protruding before connective, lower portion extremely developed, running along ventral margin of membranous portion of phallobase, divided into widely separated, rod-like pair within apical sclerotized phallobase (Fig. 1F). Capitate processes present (Fig. 1G). Support tube not carefully examined. Phallobase nearly rounded, basal 2/3 membranous, apical 1/3 sclerotized dorsally and ventrally. When everted, phallobasal conjunctiva recognizable, relatively short. First pair of phallobasal conjunctival processes rod-like, sclerotized, and pigmented, second pair fused with third as lobe-like structure at lower side of aedeagus (Fig. 1F). Aedeagus paired, and widely separated at bases. In repose condition, aedeagus retracted into phallobasal cavity except for exposed apices. Ejaculatory duct running within support bridge and through phallobasal conjunctival cavity. Isyndus obscurus Dall (Fig. 2) Abdominal segment IX with anterior opening directed anterodorsad in lateral view, dorsocaudal angle produced dorsad (Fig. 2B); slender production apex truncated, without membranous area in dorsal view (Fig. 2A). Abdominal segment X semicircular in dorsal view. Abdominal segment XI retracted into segment X. Genital plates present. Genital styles symmetrical in size and shape, rod-like (Fig. 2A, C). Phallus directed dorsad within segment IX. Connective large, distinctly angulated above middle (Fig. 2E). Support bridge with normal upper portion, lower portion rather short. Capitate processes present (Fig. 2D). Support tube not carefully examined. Phallobase entirely membranous. Phallobasal conjunctiva developed, its anterior portion connecting to apicoventral portion of support bridge; its dorsocaudal portion forming a sac, whose base connects to base of aedeagus (Fig. 2F). Phallobasal conjunctival processes unrecognizable. Ejaculatory duct running outside of phallobasal conjunctival cavity. Aedeagus paired, fused at bases, in repose condition aedeagus retracted into phallobasal cavity, with only small portion exposed (Fig. 2F, G).

4 130 植物保護學會會刊第 45 卷第 2 期 2003 Fig. 2. Isyndus obscurus Dall. (A) Abdominal segments IX-XI and genital styles, dorsal view; (B) the same, lateral view; (C) right genital style, dorsal view; (D) phallus, dorsal view; (E) the same, lateral view; (F) connective, support bridge, phallobasal conjunctiva and aedeagus, lateral view; (G) aedeagus, lateral view. Triatoma rubrofasciata De Geer (Fig. 3) Abdominal segment IX elongated quadrate in dorsal view, with narrow membranous area (Fig. 3A); anterior opening directed anterodorsad in lateral view (Fig. 3B). Abdominal segment X elongated quadrate. Abdominal segment XI retracted into segment X. Genital plates trapezoid in anterodorsal view (Fig. 3D). Genital styles symmetrical in size and shape, rod-like in dorsal view, apical 1/2 curved mesad (Fig. 3A, C).

5 The external male genitalia of the Reduviidae (Hemiptera: Heteroptera) 131 Fig. 3. Triatoma rubrofastiata De Geer. (A) Abdominal segments IX-XI and genital styles, dorsal view; (B) the same, lateral view; (C) right genital style, dorsal view; (D) genital plates, anterodorsal view; (E) phallus, dorsal view; (F) the same, lateral view; (G) aedeagus, dorsal view; (H) the same, ventral view. Phallus directed dorsad within segment IX (Fig. 3B). Connective V-shaped in dorsal view (Fig. 3E). Upper portion of support bridge medially produced ventrad; lower portion extremely developed, running along ventral margin of phallobase to its basal 2/5, then obliquely upward along dorsal margin (Fig. 3F). Capitate processes present. Support tube only appearing around ejaculatory duct. Phallobase membranous, except for sclerotized dorsocaudal area. Phallobasal conjunctiva anteriorly connecting to support bridge, posteriorly connecting to aedeagus at its longitudinal ventral margin. Aedeagus arrow-shaped in dorsal view (Fig. 3G), ovate in ventral view, sclerotized and pigmented medially, each side with an ejaculatory duct (Fig. 3H); in

6 132 植物保護學會會刊第 45 卷第 2 期 2003 repose condition situated dorsoventrally within apex of phallobase. Ejaculatory duct running outside of phallobasal conjunctival cavity. Oncocephalus sp. (Fig. 4) Abdominal segment IX elongated quadrate in dorsal view, with membranous triangular area (Fig. 4A); subquadrate, anterior opening directed cephalad in lateral view (Fig. 4B). Abdominal segment X quadrate. Abdominal segment XI retracted into segment X. Genital plates triangular in anterodorsal view (Fig. 4D). Genital styles symmetrical in size and shape; rod-like in dorsal view (Fig. 4C). Fig. 4. Oncocephalus sp. (A) Abdominal segments IX-XI and genital styles, dorsal view; (B) the same, lateral view; (C) right genital style, dorsal view; (D) genital plates, anterodorsal view; (E) phallus, dorsal view; (F) the same, lateral view; (G) apex of phallus, expanded, lateral view; (H) aedeagus, dorsal view.

7 The external male genitalia of the Reduviidae (Hemiptera: Heteroptera) 133 Fig. 5. Epidaus sp. (A) Abdominal segments IX-XI and genital styles, dorsal view; (B) the same, lateral view; (C) right genital style, dorsal view; (D) phallus, dorsal view; (E) the same, lateral view; (F) the same, expanded, lateral view; (G) support bridge, phallobase, phallobasal conjunctiva, and aedeagus, lateral view; (H) the same, dorsal view. Phallus directed dorsad within segment IX (Fig. 4B). Connective rod-like in lateral view (Fig. 4E). Upper portion of support bridge very small; lower portion running along dorsal margin of phallobase, without additional angulated one. Capitate processes present. Support tube bifurcating anteriorly (Fig. 4F). Phallobase slender, membranous except for sclerotized dorsocaudal area. Phallobasal conjunctiva connecting to a short portion of basoventral margin of aedeagus (Fig. 4G). Phallobasal conjunctival processes present. Aedeagus rod-like, slender in lateral view (Fig. 4G); single, converging to apex in dorsal view (Fig. 4H). Ejaculatory duct not running into phallobasal

8 134 植物保護學會會刊第 45 卷第 2 期 2003 conjunctival cavity. Epidaus sp. (Fig. 5) Dorsomedial portion of abdominal segment IX membranous in dorsal view (Fig. 5A); dorsocaudal portion distinctly lower in lateral view (Fig. 5B). Abdominal segment X quadrate. Abdominal segment XI retracted into segment X. Genital plates not carefully examined. Genital styles symmetrical in size and shape; rod-like, very long (Fig. 5A-C). Phallus directed caudad within segment IX (Fig.5B). Connective rod-like in lateral view (Fig. 5E). Support bridge with normal upper portion; lower portion running a short distance along ventral margin of phallobase, then upward reaching dorsal margin (Fig. 5E). Capitate processes present. Support tube bifurcating anteriorly (Fig. 5E). Phallobase membranous except for sclerotized dorsocaudal portion. Phallobasal conjunctiva connecting to aedeagus at its longitudinal ventral margin (Fig. 5G). Phallobasal conjunctival processes present. Aedeagus paired, short; fused at bases in dorsal view (Fig. 5H). Ejaculatory duct not running into phallobasal conjunctival cavity. DISCUSSION The phallobasal conjunctiva In Neocentrocnemis formosana, the phallobasal conjunctiva in an everted condition connects to the apex of the phallobase anteriorly and to the base of the aedeagus posteriorly. This position in relation to neighboring structures is found in all Hemiptera except in Gerromorpha. That is why it is determined to be the primitive character state. In Isyndus obscurus, the phallobasal conjunctiva in the repose condition is connected to the apex of the support bridge and to the base of the aedeagus by its dorsoapical sac anteriorly, and to the apex of the phallobase posteriorly. There are 2 directional changes when it unfolds: 1) The phallobasal conjunctiva connects to the apex of the support bridge anteriorly. This fixes the position of the large, membranous phallobasal conjunctiva. 2) The position of the phallobasal conjunctiva connected to the base of the aedeagus changes as the aedeagus rotates to the dorsoapical sac of the phallobasal conjunctiva. In Triatoma rubrofasciata, the phallobasal conjunctiva connects to the support bridge anteriorly and to the aedeagus in its longitudinal ventral margin posteriorly. Compared with I. obscurus, there are 2 directional changes when it unfolds: 1) The aedeagus rotates from the dorsal to the posterior portion of the phallobasal conjunctiva. 2) The phallobasal conjunctiva connected to the aedeagus changes from the base of the aedeagus to its longitudinal ventral margin. In Oncocephalus sp., the phallobasal conjunctiva connects to the aedeagus at its basoventral longitudinal margin anteriorly and to the apex of the phallobase posteriorly. It shows the same degree of changes as in T. rubrofasciata. If this form is due to the back rotation of the aedeagus, then it does not follow the rule of parsimony. That is why it is judged to be in a branched position in relation to T. rubrofasciata. Compared with I. obscurus, there are 2 directional changes when it unfolds: 1) The aedeagus retracts to

9 The external male genitalia of the Reduviidae (Hemiptera: Heteroptera) 135 connect to the apex of the support bridge. 2) The phallobasal conjunctiva connects to a short portion of the basoventral longitudinal margin of the aedeagus. Epidaus sp. exhibits nearly the same characteristics as Oncocephalus sp. The aedeagus In Neocentrocnemis formosana, it is paired, and widely separated at the bases. In Isyndus obscurus, it is paired, and fused at the bases. In Triatoma rubrofasciata, it is fused, but in ventral view, paired ejaculatory ducts are still recognizable. In Oncocephalus sp., it is very long, reaching nearly to the apex of the phallobase, which is fused, and the mid-longitudinal area is membranous. In Epidaus sp., it is rather short, and paired but fused at the bases. The ejaculatory duct In Neocentrocnemis formosana, it normally runs through the phallobasal conjunctival cavity. In Isyndus obscurus and Triatoma rubrofasciata, it is believed that the ejaculatory duct runs through outside of the phallobasal conjunctival cavity. In Oncocephalus sp. and Epidaus sp., it does not run into the phallobasal conjunctival cavity. The problem of sperm passage In Neocentrocnemis formosana, Isyndus obscurus, and Triatoma rubrofasciata, sperm have no problem passing through the ejaculatory duct within the aedeagus and the so-called gonopore (secondary gonopore sensu Dupuis, 1970 (1) ) at the apex of the aedeagus. But in Oncocephalus sp. and Epidaus sp., those routes are very doubtful: in these 2 forms of external male genitalia, the gonopore and the opening of the phallobase (phalloma mouth sensu Singh-Pruthi, 1925 (2) ) are in 2 different places. In Oncocephalus sp., the aedeagus is very long, reaching nearly to the apex of the phallobase, but no opening is recognizable in that area. In Epidaus sp., the aedeagus is rather short, and after its apices are the phallobasal cavity. Then what structure serves as the ejaculatory duct? We believe that the phallobasal conjunctival cavity plays the role of the ejaculatory duct. This is a reasonable inference and the only interpretation. Many species of Derbidae (Fulgoroidea) (3) show the same pattern as in these 2 forms, because the aedeagus is reduced or has been lost. LITERATURE CITED 1. Dupuis, C. and J. C. M. Carvalho Heteroptera. pp In: S. L. Tuxen [ed.], Taxonomist s Glossary of Genitalia in Insects. Munksgaad, Copenhagen. 2. Singh-Pruthi, H The morphology of the male genitalia in Rhynchota. Trans. Entomol. Soc. London 1925: Yang, C. T., and Chang, T. Y The external male genitalia of Hemiptera (Homoptera-Heteroptera). Shih Way Publishers, 746 pp.

10 136 植物保護學會會刊第 45 卷第 2 期 2003 멋 굮 ꗲ 맏 2003 쉹곬 ꕾ ꅝꕢ 꿍 ꗘꅇ 꿍 ꗘꅞ 듓 라 ꕚ 45ꅇ (ꕸ 냪 ꗟ ꑪ 뻇 싎뻇 ) 뿯 Neocentrocnemis formosona MastsumuraꅂIsyndus obscurus DallꅂTriatoma rubrofasciata De GeerꅂOncocephalus sp. 뭐 Epidaus sp. 뫘 ꕾ 뇔굺 맏 ꅃꙢ N. formosana, ꕾ 뭐 ꕌ 꿍 ꗘ 뫘쏾 때꽓껭멣 ꑗ 깴 ꅃ Ꙣꯡꕼ 뫘 ꅁ 깧뫫뫞덱륌 뙩 ꑊ 담냲 Ꙙ 뗄 ꅃꙢꯡꑔ 뫘 ꅁ 담냲 Ꙙ 덳담 멁뻇셡 Ꙗ 뵴 ꅃꙢꯡꑇ 뫘 ꅁ 담냲 Ꙙ 뗄 ꕎ 깧뫫뫞 ꕜ 꿠 ꅃ ( 쏶쇤뗼 ꅇ 쉹蝽곬 ꅂ 멁뻇 ꅂ ꕾ )