Rhodanthidium

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Anthidiini
Genus: Rhodanthidium Isensee, 1927
Subgenera: Asianthidium, Meganthidium, Rhodanthidium
Common name: snail-shell bees

Overview

Rhodanthidium are moderate to large sized bees, ranging from 11–22 mm in body length. They have black integument with yellow or reddish-yellow maculations on their head, thorax, and abdomen (Michener 2007).

Diversity

Rhodanthidium contains more than 13 species in three subgenera worldwide (Michener 2007); none are known to occur in the U.S. or Canada.

Diagnostic characteristics

(modified from Michener 2007)

Arolia present.
Juxtantennal carina present.
Labrum longer than clypeus.
Middle tibia with one apical spine.
Omaular carina absent.
Pronotal lobe carinate.
Propodeum without postspiricular fovea present and defined by carina.
Stigma less than twice as long as broad.
Subantennal sutures straight.
Female scopa present.
Female S6 without lateral teeth (Fig 6).
Male gonostyli have simple apices or two small teeth.
Male T7 trifid (or with 5 projections in subgenus Meganthidium) (Fig 7).
Male S4 and S5 of the sterna often have median apical combs.
Male S5 with lateral tooth (Fig 7).

May be confused with

Rhodanthidium may be confused with Pseudoanthidium (Neanthidium), due to both genera having yellow, broken medial bands on their abdomens, but differ by the presence of arolia in Rhodanthidium (Michener 2007). Benanthis also share many features with some species of Rhodanthidium. They differ in that the T7 of Rhodanthidium males have 3 or 5 teeth and Benanthis have a bilobed T7. Female Benanthis have lateral teeth on S6, while Rhodanthidium lacks teeth on S6.

Known invasives

There are no known invasives.

Host associations

Rhodanthidium visit plants within the families Asteraceae and Fabaceae (Proctor et al. 1996). Rhodanthidium siculum has been observed collecting pollen and nectar from flowers such as Galactites tomentosus, Centaurea sphaeocephala, Glebionis coronaria, and Lotus creticus (Erbar and Leins 2017).

Nesting behavior

Many species of Rhodanthidium (e.g., R. siculum) nest in empty snail shells (Peisl 1999). Females deposit sand and saliva in the navel of the shell. They then provision the shells with pollen and nectar from host flowers. Females will copulate with multiple male partners, and then lay one or two eggs within the shell, which is then closed with pieces of seashell or snail shell, saliva, and sand. They will then transport the closed shell to a safe location where it is buried, often underneath plants (Erbar and Leins 2017).

Distribution

Rhodanthidium are found from the Mediterranean area to southwestern and central Asia and central Europe (Michener 2007).

Distribution map generated by Discover Life -- click on map for details, credits, and terms of use.

<p><em>Rhodanthidium septemdentatum </em>male face, photo: C. Ritner</p>

Rhodanthidium septemdentatum male face, photo: C. Ritner

<p><em>Rhodanthidium septemdentatum </em>male lateral habitus, photo: C. Ritner</p>

Rhodanthidium septemdentatum male lateral habitus, photo: C. Ritner

<p><em>Rhodanthidium septemdentatum</em> male abdomen, photo: T. Brady</p>

Rhodanthidium septemdentatum male abdomen, photo: T. Brady

<p><em>Rhodanthidium sticticum</em> female with orange markings, photo: C. Ritner</p>

Rhodanthidium sticticum female with orange markings, photo: C. Ritner

<p><em>Rhodanthidium sticticum </em>T6 with truncate projection, photo: C. Ritner</p>

Rhodanthidium sticticum T6 with truncate projection, photo: C. Ritner

<p><em>Rhodanthidium septemdentatum </em>female T6 without impunctate median ridge, photo: C. Ritner</p>

Rhodanthidium septemdentatum female T6 without impunctate median ridge, photo: C. Ritner

<p><em>Rhodanthidium superbum </em>male T7 with five apical projections, photo: C. Ritner</p>

Rhodanthidium superbum male T7 with five apical projections, photo: C. Ritner