Paranthidium

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Anthidiini
Genus: Paranthidium Cockerell and Cockerell, 1901
Subgenera: Paranthidium, Rapanthidium
Common name: none

Overview

Paranthidium are bees with robust bodies that range in body length from 7.5–11.0 mm (Michener 2007). They are nonmetallic and have black or brown integument with white to yellow abdominal, thoracic, or facial patterns (Michener 2007). Some species have color patterning that is similar to that of a hornet (Wilson and Carril 2016). The presence of pollen-collecting hairs on the female abdomen and other characters make them easy to identify as a bee on close inspection.

Diversity

Paranthidium contains approximately 8 species in 2 subgenera worldwide. Paranthidium jugatorium, occurs in the U.S. and is rare or absent in extreme southern Canada (Michener 2007; Wilson and Carril 2016). Two species are undescribed (Michener 2007).

Diagnostic characteristics

(modified from Michener 2007)

Arolia present.
Middle tibia with a convex, lobe-like carina at apex (Fig 4).
Omaular carina absent.
Preoccipital carina absent.
Pronotal lobes carinate or lamellate.
Propodeum with fovea behind the spiracle, except in the subgenus Rapanthidium.
Male S5 with lateral combs (Paranthidium s. str.) (Fig 7).
Male T7 trilobed, the median lobe always larger than the lateral lobes (Fig 8).

May be confused with

Paranthidium may be confused with Dianthidium due to similar size, shape, and coloration, but can be easily distinguished because Paranthidium lacks omaular and preoccipital carina (Michener 2007).

Known invasives

There are no known invasives.

Host associations

Paranthidium are generalists overall, but some show some level of preference for Asteraceae (Wilson and Carril 2016).

Nesting behavior

Paranthidium are solitary bees that build nests in sandy soil by excavating their own burrows or using preexisting insect burrows, including inactive bee burrows (Evans 1993; Wilson and Carril 2016). Thin resin walls line and partition the series of cells occurring in the burrow. Small pebbles may be placed between resin layers (Evans 1993).

Distribution

Paranthidium is endemic to the Western Hemisphere, and ranges from the U.S. south to Panama (Michener 2007). The only species that occurs in the U.S., is P. jugatorium which occurs from the Atlantic Coast into the midwestern and southwestern U.S. This species has been further divided into four subspecies (Wilson and Carril 2016). Paranthidium jugatorium jugatorium occurs from New York to the Midwest; P. jugatorium lepidum occurs in Kentucky and Virginia, south to Georgia, with records in northern Florida; P. jugatorium butleri occurs in Arizona; and P. jugatorium perpictum occurs in Colorado, New Mexico, and Arizona (Wilson and Carril 2016). The remaining species in the genus occur in Mexico and Central America (Michener 2007).

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