Larval head morphology of Phycosecis litoralis (Pascoe) (Coleoptera : Phycosecidae) with phylogenetic implications

The larval head of a Phycosecis species is described and illustrated. Chara cters are compared to those found in larvae of other groups of Cucujiformia . Monophyly of all cleroid families examined is supported by several apomor phic features at least partly correlated with predacious habits: antennae d irected anteriad, absence of the mandibular mola, presence of a pedunculate seta on the mala, presence of a median endocarina, origin of antennal musc les exclusively from the head capsule, and presence of a weakly pigmented, parallel-sided gular plate. A possible apomorphy of Cleroidea excluding Phl oiophilidae is the parallel-sided, prognathous head. A sister-group relatio nship between Phycosecidae and Melyridae is supported by the presence of a plumose lacinia mobilis and secondary loss of the median endocarina. A mono phylum comprising Cleridae + Chaetosomatidae is characterised by a strongly elongated, sclerotised larval gula, the strongly protracted position of th e ventral mouthparts, and a cardo as long as or longer than the stipes. Mon ophyly of Trogossitidae is only weakly supported. Several apomorphies indic ate a sister-group relationship between Cleroidea and Nitidulidae. These tw o taxa are characterised by a fully developed maxillolabial complex, an elo ngated prepharyngeal tube, and tergal sclerotisation restricted to the prot horax and tergite IX. A tentorial bridge completely separated from the rema ining tentorium, and a maxillolabial complex with partly restricted motilit y of the maxilla are shared derived features of larvae of Cleroidea, Nitidu lidae, Coccinellidae and Endomychidae. An unusual attachment of a part of t he tentoriostipital muscle to the floor of the prepharyngeal tube is found in all cleroid and cucujoid larvae examined. Cleroidea are a well-defined m onophyletic group and may form a monophylum together with a paraphyletic as semblage of Cucujoidea. A close relationship between Cleroidea and Lymexyli dae is refuted.