title: Ultrastructural comparison of the ocelli of Sinopanorpa tincta and Bittacus planus (Mecoptera).
abstract: On the contrary to compound eyes, dorsal ocelli are poorly investigated for their ultrastructure in many insect groups, including Mecoptera. The ocellar ultrastructure of the scorpionfly Sinopanorpa tincta (Navás) in Panorpidae and the hangingfly Bittacus planus (Cheng) in Bittacidae was examined using transmission electron microscope. Both species possess three ocelli on the vertex of their heads and each ocellus has a corneal lens, some pigment cells at the outer rim of the lens, and fused rhabdoms. Beneath the corneal lens lies a single layer of corneagenous cells, which is very thick with the nuclei located proximally in S. tincta and quite thin in B. planus. A portion of rhabdom is composed of rhabdomeres from two adjacent retinula cells in S. tincta, but from four retinula cells in B. planus. Each rhabdomere comprises parallel microvilli projecting laterally from the apposed retinula cells. In addition, abundant electron-lucent granules are present at the middle part around each retinula in B. planus. Only pigment granules exist around the retinula proximally at the nucleate level in S. tincta.
authors: Key Laboratory of Plant Protection Resources and Pest Management, Ministry of Education, Entomological Museum, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors: Yao
authors: Y
authors: Wei
authors: Baozhen
authors: B
authors: Hua