Radoszkowskiana

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Megachilini
Genus: Radoszkowskiana Popov, 1955
Subgenera: none
Common name: none

Overview

Radoszkowskiana are cleptoparasites that range in body length from 10–13 mm. Females have a red abdomen, while males have a black abdomen (Michener 2007). Female’s second abdominal segment is the widest and tapers posteriorly (Michener 2007).

Diversity

Radoszkowskiana consists of four species (Michener 2007); none are known to occur in the U.S. or Canada.

Diagnostic characteristics

(modified from Michener 2007)

  • Arolia absent.
  • Axilla rounded, with a notch in between the posterior axilla and scutellar margins.
  • Preoccipital carina absent medially but present on the side of the head.
  • Pronotal lobe lamellate extending posterolaterally as a flat spine.
  • Stigma twice as long as broad or more.
  • Males have four exposed abdominal sterna.
  • Males preapical carina on T6 is strong, transverse, and denticulate.
  • Females lack a scopa.
  • Female T6 is longer than it is broad.
  • Female S6 is rounded and extends beyond T6 (Fig 5).

May be confused with

Radoszkowskiana may be confused with species in the genus Coelioxys due to tapering of the abdomen after the second segment in females, lack of scopa, and presence of preoccipital carina on the side of the head (Michener 2007). Radoszkowskiana males may also be confused with Megachile due to the blunt shape of T6, and rounded axilla (Michener 2007). Radoszkowskiana can be differentiated from these two genera based on the combination of distinguishing characteristics listed above. In addition, larval Radoszkowskiana can be differentiated from Coelioxys by the curvature of the first instar’s mandibles: Radoszkowskiana curve orally, while Coelioxys bend caudally (Rozen and Kamel 2008). Further, Radoszkowskiana can be differentiated from Megachile by the lack of ventral scopa (Ozbek and Schwarz 2016).

Known invasives

There are no known invasives.

Host associations

Radoszkowskiana is a group of cleptoparasitic bees whose only known host is Megachile nigripes (Rozen and Kamel 2007). Radoszkowskiana feed on their own chorion and the host’s yolk as first instar larvae (Rozen and Kamel 2007).

Nesting behavior

Female R. rufiventris lay their eggs in host nests of Megachile nigripes by either opening closed nests or, more likely, by entering the nest when the host is away (Rozen and Kamel 2007). Once in the nest, the female R. rufiventris lays an egg on top of the host egg, which is known to develop more slowly (Rozen and Kamel 2008). Once the cleptoparasite’s egg hatches, the larva kills the embryonic host by biting it with short, fang-like mandibles and then consumes its own chorion while staying on top of the dead host egg (Rozen and Kamel 2008).

Distribution

Radoszkowskiana are distributed from Algeria to the Trans-Caspian region (Michener 2007).

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

<p><em>Radoszkowskiana gymaopygia</em> male face, photo: C. Ritner</p>
Radoszkowskiana gymaopygia male face, photo: C. Ritner
<p><em>Radoszkowskiana gymaopygia </em>male lateral habitus, photo: C. Ritner</p>
Radoszkowskiana gymaopygia male lateral habitus, photo: C. Ritner
<p><em>Radoszkowskiana gymaopygia</em> male abdomen, photo: C. Ritner</p>
Radoszkowskiana gymaopygia male abdomen, photo: C. Ritner
<p><em>Radoszkowskiana rufiventris </em>female lateral habitus, photo: C. Ritner</p>
Radoszkowskiana rufiventris female lateral habitus, photo: C. Ritner
<p><em>Radoszkowskiana gymnopygia</em> female S6 rounded, photo: C. Ritner</p>
Radoszkowskiana gymnopygia female S6 rounded, photo: C. Ritner