The Redefinition of the Ejaculatory Reservoir s. str. in Pentatomomorpha (Hemiptera: Heteroptera)

Jing-Fu Tsai, Man-Miao Yang, and Chung Tu Yang Department of Entomology, National Chung Hsing University, Taichung, Taiwan.

Species Examined in This Investigation and the Findings. The EJR in Coridiellus figlinus (Dinidoridae) (Fig. 1) is hypothetically the starting point where the EJR begins to differentiate. Comparing Fig. 2A to Fig.1, we suggest that the EJR in the genus Coridiellus represents the most primitive character state in the Pentatomomorpha with three following reasons: 1) It is still the continuous tube-shaped structure but closed at the end and twisted. 2) The nature of the EJR is the same as the expansion of the ejaculatory duct (Fig. 1A, b). 3) Compared with other types of EJRs, it is the least modified.

Redefinition of the Ejaculatory Reservoir s. str. and Reservoir Lumen. The EJR is defined here as a structure protruding from the dorsobasal portion of the expanded ejaculatory duct at the middle of the aedeagus. The part of the structure outside the base of the aedeagus is the EJR and the other part within the aedeagus, plus the expanded ejaculatory duct, is the reservoir lumen (Fig. 2C).

Further Consideration of the Reservoir Lumen. In Cyclopelta obscura (Dinidoridae), Scutelleridae except H. curculionoides, Tessaratomidae, and Cydnidae, the reservoir lumen is separated into dorsoapical lumen and ventrobasal lumen (Fig. 2D, Fig. 3A-D). In H. curculionoides and the other remainder families of Pentatomomorpha, the ventrobasal lumen is reduced and the end of the ejaculatory duct is retracted. According to the relative position, quality as expressed in function, and features compatible with the delimitation of a monophyletic taxon, the structures found in C. figlinus and the other remainder families of Pentatomomorpha are judged homologous.

Prevailing Views of Ejaculatory Reservoir (EJR). Singh-Pruthi (1925) defined the ejaculatory reservoir as “an expansion of the ejaculatory duct at the base of the vesica [= aedeagus] present in Heteroptera” (Fig. 2B). However, Dupuis (1970) considered that the ejaculatory duct comprises two distinct parts by means of the EJR as a baseline, a proximal and a distal one, naming them the ductus seminis proximalis and ductus seminis distalis, respectively (Fig. 2B).

INTRODUCTION The higher classification of Dinidoridae is the topic of the J.F.T.’s MS thesis (Tsai, 2003). Scutelleridae, Tessaratomidae, and Cydnidae were selected as outgroups. After examining the external male genitalia, the definition of Singh-Pruthi could not be satisfactorily applied to the above-mentioned families. The major purpose of this paper is to reevaluate the terminology of male genitalia applied to the Pentatomomorpha and propose a clear definition based on comparative morphological study. Taxonomy of Pentatomomorpha followed Henry (1997) and Schuh and Slater (1995).

Comparison of Our Redefinition and That of Singh-Pruthi. There are three differences between our interpretation and that of Singh-Pruthi. 1) The original position of EJR is near the middle of the aedeagus, not at its base. 2) EJR is the structure protruding from the expanded ejaculatory duct and it is a derived structure, not an expansion of the ejaculatory duct. 3) EJR is present only in Pentatomomorpha, not in all Heteroptera. Additional explanations are given below. The position of ejaculatory duct connects to the EJR. Many species examined is the same as that of C. figlinus, i.e. connecting position near middle of the aedeagus (Fig. 3A-D). Exception of Hotea curculionoides (Scutelleridae) and the remainder families of Pentatomomorpha, the ejaculatory duct connects to the EJR at its basoventral portion (Fig. 3F-J). The presence of EJR. According to the evidence homology criterion: “Features compatible in their distribution with the delimitation of monophyletic taxa (Remane 1952)”, the similar structure (EJR) found in other infraorders is not homologous. The struts in Reduviidae (Cimicomorpha) is not EJR. It is judged as “support bridge- the differentiated structure of dorsoanterior upper portion of the phallobase (Yang and Chang, 2000). The EJR of C. figlinus is the least modified. If it is really the most plesiomorphic condition of the EJR, it is reasonable to hypothesize that it is restricted to the Pentatomomorpha.

RESULTS AND DISCUSSION

Fig. 1. Ejaculatory duct and a derived structure of the aedeagus of C. figlinus. (A) Lateral view. (B) Dorsal view. a, ejaculatory duct; aed, aedeagus; b, the expansion of the ejaculatory duct; c, part of protruding structure termed the “reservoir lumen”; d, part of protruding structure, ejaculatory reservoir; phc, phallobasal conjunctiva.

Fig. 3. Illustrations on the ejaculatory reservoir of some species in Pentatomomorpha. (A) C. obscura (Dinidoridae). (B) Chrysocoris grandis (Scutelleridae). (C) Eurostus vallidas Dallas (Tessaratomidae) (D) Adrisa sp. 1 (Cydnidae) (E) Hotea curculionoides (Scutelleridae). (F) Daulocoris formosanus (Aradidae). (G) Andrallus spinidens (Pentatomidae). (H) Daclera sp. (I) Pachyphlegyas modiglian (Lygeaidae). (J) Physopelta guttata (Largidae). hp, holding plate; other abbreviations are the same as in Fig. 2.

Fig. 2. Diagrammatic stylized illustration showing the various types of the ejaculatory reservoir in Heteroptera. (A) Based on Heteroptera without the ejaculatory reservoir. (B) Contrasts of Singh-Pruthi’s view (above labels) and Dupuis’s view (below labels) of male genitalia. (C) Based on C. figlinus (Dinidoridae), most species in Dinidoridae belong to this type. (D) Based on C. obscura (Dinidoridae), Scutelleridae, Tessaratomidae, and Cydnidae (see Fig. 3A-D). (E) Based on H. curculionoides (Scutelleridae), and other remainder families of Pentatomomorpha (see Fig. 3E-J). aed, aedeagus; dal, dorsoapical lumen; du. sm. d, ductus seminis distalis; du. sm. p, ductus seminis proximalis; ejd, ejaculatory duct; ejr, ejaculatory reservoir; phc, phallobasal conjunctiva; vbl, ventrobasal lumen.

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