A new species of Hortipes (Araneae, Corinnidae), the first spider with an insertable retrolateral tibial apophysis on the male palp

Rudy Jocqué,Arnaud Henrard,Jan Bosselaers

doi:10.5852/ejt.2012.26

Abstract

Hortipes gigapophysalis (Araneae, Corinnidae) is a new species described from both sexes from montane forest on Mt Nimba, eastern Guinea. The species is remarkable for its long, whip-shaped retrolateral tibial apophysis (RTA) on the male palp. The structure apparently has an insertable function as the epigyne of the female contains a separate set of ducts starting from a central concavity that is unique in the genus. This duct system is apparently meant to receive the supple RTA. This type of structural arrangement has never previously been found in spiders.

Highlights

With almost 70 known species, Hortipes Bosselaers & Ledoux, 1998 is one of the largest Afrotropical genera (Bosselaers & Jocqué 2000a)
The present paper describes a new species in the genus that has a remarkable male palp provided with a very long retrolateral tibial apophysis (RTA) unlike any that has been found in spiders so far
Its main function was long thought to be internally stabilising the expanded male palp during copulation, which means that the RTA locks either specific sclerites of the bulbus or between the bulbus and cymbium in order to arrest further rotation or movement (Huber 1995a: 151; Sierwald & Coddington 1988: 264)

Summary

Introduction

With almost 70 known species, Hortipes Bosselaers & Ledoux, 1998 is one of the largest Afrotropical genera (Bosselaers & Jocqué 2000a). Most of the species live in the litter layer of dense forests and woodlands, its very wide distribution from West Africa to Ethiopia in the north and to large parts of South Africa in the south. The genus is entirely absent from miombo woodland and is an excellent example of an Afrotropical spider genus with this type of distribution. The genus is remarkable as an example of the range of complexity of genitalia that is met with in many spider genera. In Hortipes, the genitalia range from quite simple structures as in H. silvarum Ledoux & Emerit, 1998 to complex configurations such as in H. sceptrum Bosselaers & Jocqué, 2000a. The genus can be considered as suitable for testing the evolution of genitalia in the context of sexual selection hypotheses (e.g. Eberhard & Huber 1998; Huber 1995a; Jocqué 2002)

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