The histomorphological structure of the male reproductive system of maize leaf weevil Tanymecus dilaticollis Gyllenhal, 1834 (Coleoptera: Curculionidae)

Abstract

The histomorphology of the reproductive system and the germ cells has been useful to establish phylogenetic relationships in many insects. However, these elements remain little known in the Curculionidae. In this study, histomorphological structure of the male reproductive system of Tanymecus dilaticollis, which is economically important, is described, illustrated using stereomicroscopy, light microscopy, and scanning electron microscopy techniques, and discussed in relation to other Coleoptera species. Results showed that distinctive features of the male reproductive system of T. dilaticollis consist of a pair of yellowish testes, a pair of seminal vesicles, a pair of vasa deferentia, an ejaculatory duct, accessory glands, prostate glands, and aedeagus. Each testis is subdivided into two testicular follicles, enclosed by a peritoneal sheath. Each follicle of the mature testes is full sperm cysts with germ cells at various stages development of spermatogenesis. The testes have four types of germ cells (spermatogonia, spermatocytes, spermatids, and spermatozoa). They are occupied by the growth zone containing spermatogonia and spermatocytes, the maturation zone containing spermatids, while differentiation zone containing spermatozoa. There is a seminal vesicle at the center of each testis. Most mature sperms are stored in the seminal vesicle. Each testis is attached to the vas deferens by a stalk‐like seminal vesicle. In the distal part, vasa deferentia fuse with the ejaculatory duct. It is linked to the aedeagus. The provided results will contribute to the understanding of the reproductive cell biology of Curculionidae.

Anatomy and histology of reproductive system of adult male mint leaf beetle Chrysolina herbacea (Duftschmid, 1825) (Coleoptera: Chrysomelidae)

“…Each follicle has stages of spermatogenesis (spermatogonia, spermatocytes, spermatids, and spermatozoa). The mature sperms pass through the testis via short channels (vasa efferentia) and are deposited in the seminal vesicle, vasa deferens, and ductus ejaculatorius (Alzahrani, Abdelsalam, Elmenshawy, & Abdel‐Moneim, 2013; Barker, 1989; Candan, Özyurt Koçakoglu, & Suludere, 2018; Cerezke, 1964; Hopkins, Steelman, & Carlton, 1993; İzzetoglu & Gülmez, 2018; Özyurt Koçakoğlu, Candan, & Güllü, 2019; Phillips, 1970; Suzuki, 1988; Wu et al, 2017).…”

“…In P. sanctipauli (Coleoptera: Scarabaeidae), there is a single pair of tubular coiled accessory glands (Diefenbach, Redaelli, & Gassen, 1998). In H. bonariensis (Coleoptera: Curculionidae), L. bonariensis (Coleoptera: Curculionidae) and T. dilaticollis paired blind‐ended tubules accessory glands and paired multilobed prostate glands are observed (Barker, 1989; Goldson & Emberson, 1981; Özyurt Koçakoğlu et al, 2019). That is, the number and view of accessory glands varies from species to species.…”

Histomorphological Structure of Male Reproductive System in Capnodis tenebrionis (Linnaeus, 1761) (Coleoptera: Buprestidae)

“…There is a seminal vesicle where mature sperms are stored at the center of each testis in T. dilaticollis (Curculionidae) (Özyurt Koçakoğlu et al, 2019) and R. ferrugineus (Dryophthoridae) (Barker, 1989;Paoli et al, 2014) but in L. bonariensis (Curculionidae) the seminal vesicle is located at the basal end of the testis (Goldson & Emberson, 1981). Moreover, the testis posterior end of C. tenebrionis is connected with vas deferens.…”

“…(Dryophthoridae) (Paoli et al, 2014), and Tanymecus dilaticollis Gyll. (Curculionidae) (Özyurt Koçakoğlu, Candan, & Güllü, 2019). However, there are remarkable anatomical varieties in male reproductive system of Coleoptera.…”

“…In C. tenebrionis, as in other species of the Buprestidae family, each testis consists of many follicular tubules (Gardner 1986). Each testis in T. dilaticollis (Özyurt Koçakoğlu et al, 2019) and Hylobius pales (Herbst) (Curculionidae) have two follicles (Hoffman & Raffa, 1992); on the other hand, they are divided into six follicles in D. monticolae (Scolytidae) and P. sanctipauli (Coleoptera: Scarabaeidae) (Cerezke, 1964;Diefenbach et al, 1998). As well as there are 8-10 follicles in each testis of Hyperodes bonariensis Kuschel (Curculionidae) and Listronotus bonariensis (Kuschel) (Curculionidae) (Barker, 1989;Goldson & Emberson, 1981).…”