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Structure and distribution of antennal sensilla in 15 species of Glossosomatidae were studied with SEM and compared to available data for species in the families Philopotamidae (16 species previously studied) and Rhyacophilidae (25 species previously studied). Comparative analyses led to 8 different sensillar types being identified among the glossosomatids: long trichoid, curved trichoid, chaetoid, styloconic, coeloconic, mushroom-like pseudoplacoid, coronary, and Böhm’s bristles. Diversity of sensilla in Glossosomatidae is lower than reported for Rhyacophilidae and comparable to Philopotamidae. A coeloconic sensillum, unique to Glossosomatidae was identified but shows no species specificity. Distribution of most sensillum types resembles that seen in the other families: There are 2 tiers of sensilla and 4 types of distribution patterns, namely specific, non-specific, fixed, and grouped in sensory fields. Comparisons of Glossosomatidae with other Trichoptera families and data on lower Lepidoptera groups indicate a putative ground plan for antennal sensory structures among Amphiesmenoptera. In contrast, comparative data indicate a significant difference between Amphiesmenoptera and Mecoptera, a member of the sister group to Amphiesmenoptera.

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A comparative SEM study of palp sensory surfaces in 25 caddisfly species representing seven families reveals seven types of sensilla: long trichoid, blunt chaetoid, campaniform, mushroom-like pseudoplacoid, petaloid, thick basiconic and thin basiconic sensilla. Long trichoid and chaetoid sensilla are present on all segments of both pairs of palps. First and second segments of maxillary palps bear groups of long and sclerotised chaetoid sensilla on their medial surface. Other segments of maxillary palps and all segments of labial palps have shorter and thinner chaetoid sensilla mainly on their ventromedial surfaces. Campaniform sensilla usually occur on the first segment of labial palps and second segment of maxillary palps. Mushroom-like pseudoplacoid sensilla may occupy all palp segments or only distal ones. Petaloid sensilla form sensory fields on apical segments of both pairs of palps in most studied species. Thick basiconic sensilla occur only in apical sensory complexes on tips of maxillary and labial palps. A comparison with the Lepidoptera suggests the similarity in palp sensilla and conservative evolution of the palp surface. The reconstructed ground plan for the palp sensory surfaces in Trichoptera and Amphiesmenoptera is provided.

Structure and distribution of antennal sensilla were studied in males of 19 species of the caddisfly family Hydropsychidae by using scanning electron microscopy (SEM). Eleven types of sensilla were found: long trichoid, chaetoid, thick chaetoid, curved trichoid, coronary, basiconic, styloconic and four types of pseudoplacoid sensilla (mushroom-like, auricillic, ribbed, and T-shaped). Thick chaetoid, ribbed pseudoplacoid, and T-shaped pseudoplacoid sensilla were found only in Macronematinae. The great diversity of pseudoplacoid sensilla originated from a mushroom-like type, which also has a variable structure. Basal flagellomeres in the majority of studied species are equipped with ventrally positioned sensory fields of curved trichoid sensilla. In contrast to Arctopsychinae and Hydropsychinae, the increased number of these sensilla in the fields was noted for Diplectroninae and Smicrideinae. Most Macronematinae show a reduction of sensory fields and a strongly decreased average number of curved trichoid sensilla on distal segments. The great differences found in the studied family probably indicate a rapid function-related evolution of the antennal sensory surface structures in the caddisfly family Hydropsychidae.