Fig 1.
Tetradonia beetles are predators of Neotropical army ants.
Shown is a Tetradonia beetle attacking an adult Eciton burchellii worker during a colony emigration. Tetradonia beetles are the only army ant myrmecophiles known to regularly kill and feed on adult workers. Photo: Daniel Kronauer; Parque Nacional Henri Pittier, Venezuela.
Table 1.
Shown is the number of host emigrations, raids and refuse deposits from which Tetradonia beetles were collected and analyzed. Numbers in parentheses give the number of different colonies of a given host species. Note that the focus of the study was to systematically sample host emigrations, while specimens were only collected opportunistically from raids and refuse deposits. Detailed sample information is given in S1 Table.
Fig 2.
Genetic assessment of species boundaries in a community of Tetradonia beetles.
(a) NJ trees based on Tamura-Nei distances (scale bars) for both mitochondrial (COI sequences, left) and nuclear DNA sequences (concatenated wg and CAD sequences, right) reveal the same five genetic clusters (i.e. candidate species), which are depicted by separately colored boxes. Ecitomorpha arachnoides (Staphylinidae: Aleocharinae: Ecitocharini), collected in an emigration of Eciton burchellii foreli, served as outgroup. Numbers in boxes show the numbers of analyzed specimens. Bootstrap support values (1,000 replicates) for major nodes are shown. (b) Histogram showing intra- and inter-specific p-distances between Tetradonia mitochondrial COI sequences. P-distances give the proportion of bases that differ in pairwise-comparisons. A barcode gap (red double arrow) separates maximum distances within- from minimum distances between species. Mean ± SD p-distances within- and between groups are shown. Abbreviations: bp = base pairs, mtDNA = mitochondrial DNA, nDNA = nuclear DNA.
Fig 3.
Drawings of different body parts of Tetradonia lizonae (a-f), T. laselvensis (g-l), T. laticeps (m-o), T. tikalensis (p-r) and T. cf. marginalis (s-u). Head and pronotum (a, g); male tergite VIII (b, h); median lobe of aedeagus in lateral view (c, i, m, p, s); median lobe of aedeagus in ventral view (d, j, n, q, t); apex of paramere (e, k, o, r, u); spermatheca (f, l).
Fig 4.
Host preference, colonies exclusively occupied by a single Tetradonia species, and relative co-occurrence of Tetradonia species at La Selva Biological Station, Costa Rica.
(a) White numbers in cells depict host preference (or beetle prevalence) evaluated as the proportion of colonies of a given host species in which a given Tetradonia species was collected. (b) Species exclusivity in colonies reflects the proportion of colonies of a given host species in which we found only a single Tetradonia species, relative to the total number of sampled colonies of that host, but excluding those colonies in which no Tetradonia specimens were found at all (see Table 1). For example, we exclusively found T. laticeps in 5 colonies out of 8 E. vagans angustatum colonies sampled, and 6 sampled E. vagans angustatum colonies contained some Tetradonia beetles (i.e., 5/6 = 0.83). (c) To quantify the level of relative co-occurrence of different Tetradonia species, we first counted the number of host colonies that were simultaneously parasitized by a given species pair (for absolute number of co-occurrence events see S2 Fig). To account for differences in species prevalence, we divided the total number of co-occurrence events for a given species pair either by the number of host colonies in which the more prevalent partner (lower left) or the less prevalent partner (upper right) was found. For instance, out of the 5 colonies in which T. tikalensis was found, it co-occurred in 4 of them with T. cf. marginalis, the latter of which was found in a total of 28 colonies (i.e., standardized for more prevalent partner: 4/28 = 0.14; standardized for less prevalent partner: 4/5 = 0.80). Differential shading corresponds to the white numbers in cells ranging from white (value 0) to black (value 1). Photographs depict frontal head views of Eciton soldier workers and dorsal views of Tetradonia beetles for the different species. Abbreviations: E. ham. = Eciton hamatum, E. bur. f. = Eciton burchellii foreli, E. luc. c. = Eciton lucanoides conquistador, E. vag. a. = Eciton vagans angustatum, E. mex. = Eciton mexicanum s. str., E. dul.c. = Eciton dulcium crassinode, T. lat. = Tetradonia laticeps, T. mar. = Tetradonia cf. marginalis, T. tik. = Tetradonia tikalensis, T. las. = Tetradonia laselvensis, T. liz. = Tetradonia lizonae.