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Female Forktail

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  • Robert Larsen
    Hi Lynn, I was just looking at your forktail female and comparing it with Walker s illustrations of Ischnura. Especially the illustration on Plate 20, fig. 3c
    Message 1 of 1 , Jun 26, 2005
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      Hi Lynn,

      I was just looking at your forktail female and
      comparing it with Walker's illustrations of Ischnura.
      Especially the illustration on Plate 20, fig. 3c in
      (The Odonata of Canada and Alaska). Due to the thin
      humeral stripe and the abdominal markings along with
      the large postocular spots yours could be the immature
      gynomorphic (heterochromatic) female of the Plains
      Forktail (Ischnura damula) as in Walker's 1953
      illustration. That is my best guess.

      I have noted that several species of Ischnura, in the
      immature andromorph females, that there is an early
      stage where these females show bright red coloration
      to the pale areas and not the typical orange. I have
      observed this in Ischnura denticolllis and Ischnura
      hastata, and those females are found in copulation
      with mature males before the annual monsoon rains
      here. According to Corbet this mating of mature males
      with immature females is a sign of long-range female
      migrants. Also, the population of the andromorph
      females appears to decline during the summer months
      here in southern New Mexico.

      About three years ago I had sent a note to Philip
      Corbet about the long-range migrant reproductive
      behavior in Ischnura hastata females. He had sent a
      note back about Cordero's finds of female I. hastata
      on the Azores off of Spain. Evidently, the female I.
      hastata are long-range migrants that can reach the
      Azores, furtilized or unfertilized, and then reproduce
      by parthenogenesis on those islands. From reading the
      se-odonata site today I see that Cordero has just
      published his finds in (Nautre).








      Robert R. Larsen
      906 E. Orange St.
      Roswell, New Mexico 88201-7440
      USA


      Phone: 1-505-623-5548
      Regular e-mail: roblrsn@...

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