Chorosoma schillingii

Chorosoma schillingii

First instar (Figs. 29, 45, 47, 63–66). Sternum 3: median long trichobothrium, middle short trichobothrium, and lateral precursor seta medially in wide V-shaped pattern. Sternum 4: median long trichobothrium, middle short trichobothrium and lateral long trichobothrium medially in transverse line. Sternum 5: median short trichobothrium, middle long trichobothrium, and lateral long trichobothrium laterally in transverse line. Sternum 6: median short trichobothrium, middle long trichobothrium, and lateral long trichobothrium laterally in transverse line. Sternum 7: only two trichobothria present, median short trichobothrium and lateral long trichobothrium laterally in transverse line.

Second instar to adult (Figs. 30–33, 67–71). Sternum 3: median long trichobothrium, middle long trichobothrium, and lateral short trichobothrium in wide V-shaped pattern. Sterna 4–7: trichobothrial pattern identical to that of 1 st instar.

Variation. Several differences from the general trichobothrial pattern described were recognized. Four trichobothria arranged asymmetrically in a transverse line on only one side of sternum 4 occurred in several Chorosoma schillingii adults. The following unusual arrangement was recognized in several specimens of the 3 rd – 5 th instars and the adults of both species — the trichobothria on one side of the sternum 5 or 6 are not in a straight line but the middle is distinctly more anterior or more posterior than the others. Also, in one specimen of the 1 st instar of C. schillingii, we found a precursor seta on one side of sternum 5 in the position of a median short trichobothrium.