The function of lacinia of Dipseudopsidae derived from evidence in morphology and sensilla (Trichoptera)

Abstract

SummaryThe Trichoptera Dipseudopsidae are known to possess a proboscis reminiscent of that of Lepidoptera, a sister group of Trichoptera. The aim of our study is to discover whether the proboscis of Dipseudopsidae can function like that of Lepidoptera, by studying its morphology with scanning electron microscopy. Three species have been observed: Dipseudopsis oliveri Oláh & Johanson, 2010; D. lamellata Martynov, 1935, and D. modesta Banks, 1911. Their mouthparts are identical and reveal the same types of sensilla; they differ only by their length and the number of sensilla. A detailed description is offered of the D. oliveri species alone for which we possess specimens of both sexes. The maxillary lobes of D. oliveri are considerably lengthened and are thought by various authors to represent either laciniae or galeae; they are not concave and possess no linking structures and, being distant from one another, they cannot constitute a functional proboscis. Their sensory equipment, comprising exclusively uniporous sensilla styloconica with a presumed gustatory function, makes them resemble the galeae composing the proboscis of Lepidoptera. The haustellum, though reduced in size, bears at its distal extremity uniporous sensilla styloconica which are similar to those of the maxillary lobes. The existence of sensilla styloconica with a flattened stylus creates a similarity between Dipseudopsis and the most advanced Lepidoptera. The maxillary and labial palps possess an abundance and diversity of tactile and gustatory sensilla and a great number of sensilla campaniformia. Their importance is considerable because these very long palps, and especially the maxillary palps, are the first to enter into contact with the food. The total absence of multiporous olfactory sensilla in Dipseudopsis is noteworthy.