ISSN 2816-6531

A new case of gynandromorphism in the Halictus simplex species group (Hymenoptera: Halictidae)

Thomas  
Brau  
authors orcid
Paolo  
Rosa  
authors orcid
Frédéric  
Carion  
authors orcid
Simone  
Flaminio  
authors orcid
Guillaume  
GHISBAIN  
authors orcid
Tags: Apoidea, Arthropoda, Gynander, Gynandromorph, Halictidae, Halictus (Monilapis) simplex, Hymenoptera, Insecta, Italy, sweat bee
Number 37, 
9 December 2024

Introduction

Gynandromorphism is a condition in which an individual exhibits both male and female phenotypic traits. Among Hymenoptera, bees (Anthophila) account for numerous documented cases, with gynanders identified across six of the seven global bee families (Michez et al, 2009). Within the Halictidae, several cases have been documented (Andrewes, 1946; Hohndorf, 1931; Krichilsky et al, 2020; Leclercq, 1953; Popov, 1937; Saunders, 1901; Wcislo et al, 2004). Further discoveries of gynanders in this family can provide valuable insights into associating male and female characteristics, particularly within taxonomically challenging groups such as Halictus (Monilapis) Cockerell, 1931.

Results and Discussion

One Halictus Latreille gynander specimen collected in Gallinaro (Italy) on July 20th, 1983, was found in the entomological collection of the University of Mons, Belgium. This specimen is placed within the subgenus Monilapis based on its convex gena (Fig. 1c) and the prominent punctation with shiny interspaces on the propodeum laterally (Fig. 1d). The species is part of the Halictus simplex species group, in which species delineation is only possible in males. This specimen has the particularity to be a gynander with a mosaic pattern, i.e. with features distributed randomly across the body. Most tissues of the specimen exhibit female characteristics (Fig. 1a,f), while male morphological features are limited to the left antenna and to the genae, which are both convex (i.e. a male feature in the Halictus simplex group). Although the structure and length of the right antenna are typical of that of a female, with 12 properly developed articles, an emerging atrophied 13th segment can be observed, this segment being partially fused to the 12th (Fig. 1b). Furthermore, while the hind legs exhibit female structural traits, including well-developed scopa, they display a coloration typical of males (Fig. 1e).

Over the past 123 years, only three instances of gynandromorphy have been documented in the genus Halictus, including in the simplex group (Leclercq, 1953; Popov, 1937; Saunders, 1901). Further discovery of gynanders in this genus could be valuable opportunities for identifying new diagnostic criteria for delineating species. In the studied case, the distinct coloration and morphology of this specimen's legs also offer insights into Halictus development, indicating that the coloration and structure of legs occur as separate developmental pathways at the embryonic level. The synthesis of all variations observed in cases of gynandromorphism and teratogenesis will serve as a foundation for future research aimed at uncovering the embryological and molecular mechanisms underlying these phenomena.

Material

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