NATURAL HISTORY, CLASSIFICATION, RECONSTRUCTED PHYLOGENY, AND GEOGRAPHIC HISTORY OF PYTHO LATREILLE (COLEOPTERA: HETEROMERA: PYTHIDAE)

Abstract

The classification of the nine world species of Pytho Latreille is reviewed by study of adult, larval, and pupal stages. Keys are provided for separation of species in these three life stages. Taxonomic changes (senior synonym in brackets) include synonymy of P. fallax Seidlitz 1916 [= P. niger Kirby 1837]; P. americanus Kirby 1837 [= P. planus (Olivier 1795)]; P. deplanatus Mannerheim 1843 is transferred from a junior subjective synonym of P. depressus (Linnaeus 1767) to a junior subjective synonym of P. planus (Olivier 1795). Lectotype designations are provided for the following: P. seidlitzi Blair 1925; P. nivalis Lewis 1888; P. niger Kirby 1837; P. fallax Seidlitz 1916; P. abieticola J. Sahlberg 1875; and P. americanus Kirby 1837. Eight larval stage, and 12 adult stage characters were selected for cladistic analysis. Lacking out-group material, pupal characters were not analysed. Character states were polarized using a generalized out-group composed of the three other genera of Pythinae (all monobasic). Phylogenetic analysis based on these 18 characters suggests four monophyletic species-groups: P. seidlitzi group (P. seidlitzi Blair — North America); P. kolwensis group (P. strictus LeConte – North America, P. kolwensis C. Sahlberg —Fennoscandia and the U.S.S.R., P. nivalis Lewis — Japan); P. niger group (P. niger Kirby — North America, P. abieticola J. Sahlberg — Europe, P. jezoensis Kôno — Japan); P. depressus group [P. planus (Olivier, 1795) — North America, P. depressus (Linnaeus, 1767) — Europe and the U.S.S.R.]. Larval stage synapomorphies are relatively more important in defining the species-groups than are those of the adult stage. The ancestor of Pythidae may have been associated with Coniferae as early as the Jurassic. The common ancestor of Northern Hemisphere Pythinae became isolated upon Laurasia once separation from Gondwanaland occurred near the end of the Jurassic. Two of the species-groups have similar disjunctions in North America, Europe, and Japan. The relatively eastern distributions of the North American member of each suggests that the ancestor of each species-group was Euramerican, and underwent vicariance with the opening of the North Atlantic in the Middle Cretaceous. The present distribution of both species-groups is thought to have been caused by the same vicariant event. The ancestor of the P. depressus group, which is presently circumboreal, was probably widespread and could have been Asiamerican in distribution. In the middle to late Tertiary, evidence suggests that Beringia was covered with coniferous forest, and the ancestor of the P. depressus group probably extended across this land bridge. Final separation between any North American and European/Asian species occurred in the Late Miocene or Pliocene, when a cooling climate made possible the evolution of treeless tundra in the north.

Patterns of animal dispersal, vicariance and diversification in the Holarctic

“…However, there appears to be an emerging consensus that these ideas are incorrect and that the speciation rate was actually lower in the Pleistocene than in any other period. For instance, most of the insect fossil record from the Quaternary corresponds to extant species, whereas the youngest beetle fossils, which can be safely assigned to extinct or ancestral species, date back to the Late Miocene (Mathews, 1977;Coope, 1970;Spanton, 1988;Asquith & Lattin, 1990;Pollock, 1991). Similarly, Voelker (1999a,b) argued that the Pleistocene glaciations had little effect in generating modern species of passerine birds.…”

Comparative study of larvae of Tenebrionoidea (Coleoptera: Cucujiformia)

“…All segments with distinct anterior ridges (= parabasal ridges sensu Pollock, 1991) with median processes [see Fig. 1d (indicated by arrow) and Pollock, 1991]. Segments II-VII with short, paramedian, longitudinal ridges.…”

Morphology of immature stages of Prostomis mandibularis (Coleoptera: Tenebrionoidea: Prostomidae)

“…A distinct molar tooth is present on the left mandible of larvae of Prostomidae, Pythidae, Pyrochroidae, Inopeplidae and Othniidae (Young, 1991;Pollock, 1991Pollock, , 1995Pollock & Lawrence, 1995). Larvae of Prostomidae, Boridae, Mycteridae and Pyrochroidae are characterised by a tho rax, which is narrower than the head and the abdomen (Lawrence, 1991;Pollock, 1991), and the abdominal seg ment IX forms a plate-like structure, which articulates with segment VIII (Fig. 10e, f) (Lawrence, 1991;Young, 1991;Costa et al, 1998;Pollock et al, 2000).…”

“…Tergum IX extends to the ventral side and forms a plate together with the urogomphi, which articulates with segment VIII. The lateral sides of the segment and the urogomphi are covered with tubercles with a short bristle inserted on their apex (Pollock, 1991) (Figs 10e-f). A long seta inserts in the middle of the lateral side (Fig.…”

“…11c). Two pairs of symmetrically placed tubercles, each bearing a long seta, are present at the anterior margin (tubercles: see Pollock, 1991) (Fig. 11c).…”