Reproduction, egg morphology and development observed in two Australian penicillate millipedes, Lophoturus queenslandicus (Lophoproctidae) and Phryssonotus novaehollandiae (Synxenidae) (Diplopoda)

Lophoproctid and synxenid millipede species observed in this study showed clear differences in their
sexual reproduction, including sperm web structure, egg morphology and development compared with species from
Polyxenidae. Male Lophoturus queenslandicus (Lophoproctidae) produce a single spermatophore on a sperm web
without signal threads due to their lack of silk-producing coxal glands. Females of this species lay fewer eggs and differ
in their egg cluster arrangement, which includes nest trichomes for protection. Lophoproctid chorion has a thin
protective membrane and the pupoid has fused papillae covering the entire anterior region and an aperture bordered
by protective papillate sensilla is present at the apex of the pupoid. Lophoproctid millipedes have a comparatively short
intermoult period between stadia. In contrast, male Phryssonotus novaehollandiae (Synxenidae) produce two
spermatophores separated by a large gap on their sperm web, with signal threads that are less obvious. Synxenid chorion
and pupoid stages were unique; the chorion was tough and thick and the pupoid had anterior projections without an
aperture bordered by sensilla, unlike those observed in lophoproctid and polyxenid millipedes. This study extends
knowledge of the reproduction of species from three major millipede families from the Suborder Polyxenida
(Penicillata: Diplopoda). Additionally, the results indicate that the reproductive strategies of Australian lophoproctid
and synxenid species are adapted to their harsh environment.