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Exomalopsis guide updated

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  • Michael Orr
    Hello all, This guide has been nearly entirely redone with the inclusion of the Western US species, as in its former state it only included the one Eastern
    Message 1 of 1 , May 9, 2011
      Hello all,


      This guide has been nearly entirely redone with the inclusion of the Western US species, as in its former state it only included the one Eastern species E. similis. This was carried out through a combination of observation and reference to Timberlake's 1980 work on the group, with necessary loans acquired from the Logan lab. Unfortunately, sufficient males were not available for a proper treatment of the gender, making the guide only functional for females in its current state. It has also been suggested that the species E. tibialis may be a junior synonym, based upon both its rarity and the lack of female specimens. If you have any information suggesting otherwise, it would again be greatly appreciated here.

      This guide can be found at the following URL:
      http://www.discoverlife.org/mp/20q?guide=Exomalopsis

      And for convenience's sake, here is the full list of characters and what I've scored for each of them:

      Female, rear leg, color of hairs on outer face of the basitarsi
      Entirely white to pale yellowish (similis, birkmanni, hurdi, snowi, solani, solidaginis)
      With a significant amount of darker, blackish hair present dorsally (analis, dimidiata, snowi)

      Female, Subgenus Stilbomalopsis vs others
      Subgenus Stilbomalopsis - Pitting near the anterior rim of the clypeus much sparser than in basal region, often with interpit distance reaching several pit diameters - Scutum almost entirely smooth and very shiny, nearly mirror-like in posterior half of scutum, this unpitted area making up roughly half the longitudinal length of the scutum when measured at the midline - Normally without distinct pits near the posterior rim of the scutum, at most with very fine and sparse pinprick pits that are hardly visible even at high magnification - T2 largely unpitted and shiny, with more than half of its median longitudinal length devoid of pitting (birkmanni, dimidiata, hurdi, solani, solidaginis)
      Other subgenera - Pitting near the apical rim of the clypeus equal or nearly equal in density to that of the basal region - Scutum densely to sparsely pitted throughout, if with any less densely pitted area in the posterior area of the scutum then it is much less than half the length of the scutum - Most often with distinct pits near the posterior rim of the scutum - T2 with pits going all the way to the rim or very nearly so (analis, similis, snowi)

      Female, head, F1 antennal length - Note, use the minimum length of F1
      F1 fully 2X longer than F2, or greater (birkmanni)
      F1 obviously greater in length than F2, at least nearing 1.5x its length but less than 2X (birkmanni, dimidiata, hurdi, similis, snowi, solani, solidaginis)
      F1 equal in length to F2, or nearly so (analis, snowi, similis)

      Female, abdomen, T3, form of light apical transverse hair bands
      Hair band never reaching the apical rim, although it is closer at the sides than in the middle, and there may be some sparse hairs along the rim which do not form a dense band (snowi)
      Hair band medially not reaching the apical rim, although it does at its lateral sides (analis, similis)
      Hair band reaching the rim throughout, not noticeably farther from the rim in the center of T3 that the sides (birkmanni, dimidiata, hurdi, solani, solidaginis, similis)

      Female, thorax, middle leg, tibia, hair color on the OUTER surface
      All white to off-white, except sometimes for a very slightly browned apical patch (dimidiata, hurdi, solani, solidaginis)
      With obviously darker hairs mixed in, these dark hairs most often BROWNISH in coloration and sometimes very close to black, but never with ANY black hairs (birkmanni, dimidiata, hurdi, similis, snowi, solidaginis)
      With any BLACK hairs present, ranging from a small amount to the majority, but almost always obvious (analis, similis)

      Female, E. birkmanni vs E. solani
      E. birkmanni - Midtibia with extensive darker hairs, these brownish hairs extending almost the entire length of the segment while also usually extending across the entire transverse width of the outer face - With much more yellow-orangish hair on the head and thorax, this most visible on the scutellum where the hair stands in contrast with the whiter hairs of the central tuft of the metanotum
      E. solani - Midtibia with slightly browned hairs restricted only to the apical half of the segment, while usually not extending across more than half of the outer face - With much more whitish hair on the head and thorax, this most visible on the scutellum where the hair appears only slightly darker than that of the metanotum if at all different

      Female, E. birkmanni vs E. solidaginis
      E. birkmanni - Midtibia with distinct, dark brown hairs on outer face - Pits on the lateral faces of the propodeum much coarser and more densely spaced, averaging under one pit diameter in interspace distance anteriorly and becoming less dense posteriorly - Integumental color of abdomen always black to dark brown and opaque - In direct comparison, larger, usually nearing or equal to 12mm
      E. solidaginis - If with any brownish hairs on outer face of midtibia, they are a very light brown - Pits on the lateral faces of the propodeum finer and sparsely spaced, averaging more than one pit diameter in interspace distance throughout - Integumental color of abdomen often, but not always, transparently reddish-orange - In direct comparison, smaller, never reaching 10mm

      Female, E. solani vs E. solidaginis - CAREFUL, very difficult to separate pair
      E. solani - Rear border of the mesepisternum with pit spacing of at most one interpit diameter, this area being only slightly less densely pitted than the anterior area of the mesepisternum - In direct comparison, slightly larger - According to Timberlake, the middle joints of the flagellomeres are slightly longer than wide, and the basal area of the propodeum has few pits
      E. solidaginis - Rear border of mesepisternum with pit spacing much sparser than in the anterior portion, often, but not always, with greater than one pit diameter in interpit spacing - In direct comparison, slightly smaller - According to Timberlake, the middle joints of the flagellomeres are about as wide as long, and the basal area of the propodeum is unpitted

      Female, head, distance between lateral ocelli and medial ocellus, using the widest diameter of the medial ocellus
      Small, distance less than the diameter of the medial ocellus (analis, birkmanni, similis, snowi)
      Moderate, distance about equal to the diameter of the medial ocellus (birkmanni, hurdi, solani, solidaginis)
      Large, distance greater than the diameter of the medial ocellus (dimidiata, hurdi, solani, solidaginis)

      Female, E. analis vs other species
      E. analis - Hairs of vertex primarily black, or nearly so - Pronotal lobe with at least some blackish hairs - Scutellum largely or entirely black pubescent
      Other species - Hairs of vertex nearly entirely white or yellowish, sometimes a light brown - Pronotal lobe with only light hairs, ranging from white to light brown - Scutellum often with small amounts of black hairs in the interior, but still nearly entirely light

      Female, thorax, tegula, color
      Tegula dark, black or dark brownish, and usually opaque (analis, birkmanni, dimidiata, hurdi, solani, solidaginis)
      Tegula light, orange or light brownish, usually transparent such that the wing base below is mostly visible (similis, snowi, solidaginis)

      Female, subgenus Stilbomalopsis - E. dimidiata and E. hurdi vs Other Stilbomalopsis species
      E. dimidiata and E. hurdi - On the hind basitarsi, there is always dark brown to black hair on the INNER FACE - In E. dimidiata, this blackish hair is also found on the outer face, and in E. hurdi there is usually a blackish patch of hair located on the dorsal edge of the basitarsus, this hair being darker than the dark brown hairs of the inner face
      Other Stilbomalopsis species - On the hind basitarsi, the hair of the INNER FACE is at most a burnt orange color which does not reach the darkness of the hairs found on the inner face of the basitarsi of E. hurdi and comes nowhere close to the darkness of its dorsal black hairs or those found on the basitarsi of E. dimidiata

      E. tibialis vs other species
      E. tibialis - This is a rare Southwest bee with very few records, only found in TX for the United States - The author of this guide was unable to locate or verify the existence of any identified female specimens, and it is possibile that this may not be a legitimate species
      Other species - More common and widespread, always choose this option unless you have a lot of evidence for concluding the specimens are E. tibialis

      If you've read over the characters and found anything questionable, or have any suggestions for either diction changes or additional characters, please contact either myself (mco25@...) or Sam Droege (sdroege@...). We only have so many specimens of each species available to us, so we always welcome any user feedback that might benefit the resolving power or clarity of the guides.


      -Michael


      Sam makes me write poems
      But I want to play with bees
      So I choose haiku
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