Weaving through a cryptic species: Comparing the Neotropical ants Camponotus senex and Camponotus textor (Hymenoptera: Formicidae).

Camponotus senex (Fr. Smith 1858) and Camponotus textor Forel, 1899 are commonly confused species in the New World tropics. We provide morphological characteristics based on the larvae and adults, behavioural differences, together with evidence from molecular markers (cuticular hydrocarbon profiles, venom differences, nuclear ribosomal ITS-1, and mtDNA COI sequence comparisons) to separate the two species, demonstrating they are not immediately closely related. In conclusion we suggest new reliable morphological characters which can benefit from deeper phenetic analysis, and support the contextual usefulness of non-morphological tools in resolving sibling ant species.

On the morphology of the digestive system of two Monomorium ant species.

The digestive system of adults and mature larvae of two ant species of Monomorium Mayr (Hymoneptera: Formicidae) were described with the aid of light and scanning electron microscopy, as there is a lack of studies in this area. These two ant species are recurrently found in urban habitats and are known as 'tramp species,' as they cause problems in households, businesses, and hospitals. The most interesting finds of the present study include the existence of spinules in the crop of adults, and the number of Malpighian tubules and rectal pads was constant among different castes, ages, and species.

Compared morphology of the immatures of males of two urban ant species of Camponotus.

The immatures of males of two species of Camponotus ants (Hymenoptera: Formicidae) are described and compared by light and electron microscopy. The numbers of larval instars were determined: Camponotus rufipes Fabricius (Hymenoptera: Formicidae) have four instars; and Camponotus vittatus Forel have three. Male larvae of the two species are similar to previously described Camponotus larvae, sharing the following traits: basic shape of body and mandible, presence of 'chiloscleres', 'praesaepium' (some specimens), labial pseudopalps, and ten pairs of spiracles. However, larvae of the two species can be separated by bodily dimensions and based on their hair number and types. Worker larvae of C. vittatus previously described are extensively similar to male larvae, with only a few inconspicuous differences that may result from intraspecific variation or sexual differences.

On the morphology of the worker immatures of the leafcutter ant Atta sexdens Linnaeus (Hymenoptera: Formicidae).

Leafcutter ants of the genus Atta Fabricius are serious agricultural pests. Morphological studies of immature stages within this group are few, and the data provided for species of considerable importance are usually incomplete. In this study, the immatures of Atta sexdens Linnaeus are described and compared using light and scanning electron microscopy. Only specimens from founding stage colonies (i.e., lacking adult workers) were used. The existence of four larval instars was estimated by a frequency plot of maximum head widths, and the larvae of different instars differed from each other mainly by their bodily dimensions. Worker larvae belonged to two distinct morphological castes: (1) gardeners and nurses and (2) within-nest generalists. The worker larvae described in this study differed from a previous description of the same species by the following traits: the existence of a genal lobe, the number of clypeal hairs, the presence of two hairs on the ninth abdominal somite, the presence of hairs on the anterior surface of the labrum, and the shape of the maxillary palpus. This study provides a comparative analysis of immature stages of A. sexdens that may be relevant to future morphological and biological studies of the Attini.

Bait and habitat preferences, and temporal variability of social wasps (Hymenoptera: Vespidae) attracted to vertebrate carrion.

In addition to feeding on carrion tissues and fluids, social wasps can also prey on immature and adult carrion flies, thereby reducing their populations and retarding the decomposition process of carcasses. In this study, we report on the occurrence and behavior of social wasps attracted to vertebrate carrion. The collections were made monthly from September 2006 to October 2007 in three environments (rural, urban, and forest) in six municipalities of southeast Brazil, using baited bottle traps. We collected Agelaia pallipes (Olivier, 1791) (n = 143), Agelaia vicina (Saussure, 1854) (n = 106), Agelaia multipicta (Haliday, 1836) (n = 18), and Polybia paulista Ihering, 1896 (n = 3). The wasps were observed feeding directly on the baits and preying on adult insects collected in the traps. Bait and habitat associations, temporal variability of social wasps, and possible forensic implications of their actions are discussed.

Description of the immatures of the ant, Myrmelachista catharinae.

The Neotropical ant genus Myrmelachista Roger comprises 69 described species and subspecies, and still is a poorly studied group. Larvae play a paramount role in colony nutrition in social hymenopterans and bear considerable value in the reconstruction of group phylogenies, however, they are generally neglected. Larvae of different instars of Myrmelachista catharinae Mayr (Hymenoptera: Formicidae) are herein described in detail by light and scanning electron microscopy. The number of larval instars was estimated as three based on the frequency distribution of maximum head capsule widths. The described larvae confirmed some traits typical of the genus: general shape of body and mandibles, general aspect and distribution of body hairs, and the number of sensilla on the palps and galea. Differently from other Myrmelachista larvae previously described, M. catharinae presented two distinct kinds of second instars, some additional types of body hairs, different number of antennal sensilla, and a distinct labrum shape. M. catharinae presented ten pairs of spiracles, which is the first record for this genus.

Description of the immatures of workers of the ant Linepithema micans Forel (Hymenoptera: Formicidae).

Linepithema micans Forel is a poorly studied species that is now considered a pest in vineyards in South Brazil. Larval characters have been used in a few phylogenetic studies, and their importance greatly depends in the amount of available information on different species. This study presents a complete panorama on the external morphology of the immatures of L. micans based on observations by light and scanning electron microscopy. The number of larval instars was estimated as three based on the frequency distribution of head widths of 965 larvae. Larvae of L. micans were similar to other Linepithema Mayr in the general format of body and mandibles, presenting a dorsal abdominal protuberance, nine pairs of spiracle, and unbranched hairs. On the other hand, L. micans was unique for having shorter hairs, predominantly denticulate, intraspecific variation in the number of antennal sensilla and in the types of sensilla on the labial palps were reported.

General morphology and ultrastructure of the venom apparatus and convoluted gland of the fire ant, Solenopsis saevissima.

A group of 13 species of the genus Solenopsis is markedly difficult to assess taxonomically, although they are of considerable economical and medical importance in some countries where some of them were introduced. These ants are aggressive and their venomous stings can be very allergenic. The venom apparatus has been described in fine detail for only two of these species, and differences in this structure among the different species might prove useful as taxonomic characters. The venom apparatus of Solenopsis saevissima Smith (Hymenoptera: Formicidae) is herein described with the aid of light and electron microscopy techniques, and compared to that of S. invicta and S. richteri. The cellular organization of the different parts present differences that suggest functional specialization. In general, the different tissues were abundant in vesiculae and mitochondria, but presented little endoplasmic reticulum and few ribosomes, probably because they produce little protein. The length of the free filaments of the venom gland and the width of their internal ducts seems to vary from what was described for S. richteri, but this may be of little use to taxonomy.

Morphological description of the immatures of the ant, Monomorium floricola.

Some ant species of the genus Monomorium Mayr occur worldwide and are considered important urban pests. The larvae of only a few species of this genus have been described, and these descriptions are either superficial or incomplete. This study aimed to determine the number of larval instars and describe the immature stages of the ant Monomorium floricola Jerdon (Formicidae: Myrmicinae). Specimens were analyzed and measured using light and scanning electron microscopy. Three larval instars were found, and all larvae had pheidoloid bodies with ectatommoid mandibles, consistent with other Monomorium species described previously. Five types of body hairs were described, and their distribution was instar-specific. Body and mandible dimensions of the larvae also were constant for each instar. Like other Myrmicinae, the larvae did not create a cocoon. Some of differences among the hair types and sensilla were observed by comparing the samples with larvae of other species in the genus, and these differences may have taxonomic utility.