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The skeleton and the relationships of Libanopycnodus wenzi gen. et sp. nov. and of Sigmapycnodus giganteus gen. et sp. nov., two pycnodontiform fishes from the marine Cenomanian (Late Cretaceous) of Lebanon, are studied in detail. Both species belong to the family Pycnodontidae, as shown by their parietal brush-like process. Some osteological characters (bifid cloacal scale, large well visible dilatator fossa surrounded by the dermosphenotic and the dermopterotic, etc.) indicate that they are members of the subfamily Pycnodontinae. Libanopycnodus gen. nov. has the preopercle much deeper than the exposed region of the hyomandibula-dermohyomandibula and is the most primitive genus of this lineage. Sigmapycnodus gen. nov. is one of the most advanced members of the subfamily. It shares with Oropycnodus Poyato-Ariza & Wenz, 2002 and Pycnodus Agassiz, 1833 an apomorphy not present in the less specialized Pycnodontinae, the arcocentra in hypercomplex contact.
The osteology of Rhinopycnodus gabriellae gen. and sp. nov., a pycnodontiform fish from the marine Cenomanian (Late Cretaceous) of Lebanon, is studied in detail. This new fossil genus belongs to the family Pycnodontidae, as shown by the presence of a posterior brush-like process on its parietal. Its long and broad premaxilla, bearing one short and very broad tooth is the principal autapomorphy of this fish. Within the phylogeny of Pycnodontidae, Rhinopycnodus occupies an intermediate position between Ocloedus and Tepexichthys.
The osteology of Acrorhinichthys poyatoi gen. et sp. nov., a pycnodontid fish from the marine Cenomanian (Late Cretaceous) of Lebanon, is studied in detail. The new fossil genus belongs to the order Pycnodontiformes, but is less evolved than the Pycnodontidae. It still exhibits a few bony plates (= tesserae) in the gular region, 3 teeth on the premaxilla and 5 teeth on the dentary, and its parietal is devoid of a brush-like process. It shares a few characters with Akromystax, the most primitive taxon within Pycnodontidae, characters lost in the other members of the family.
Tynommatidae, n. stat., elevated from Tynommatinae, is established as a schizopetalidean family encompassing the western North American callipodidans previously assigned to the Mediterranean Schizopetalidae. It is considered a valid taxon despite somewhat anatomically dissimilar subfamilies, and Colactidinae, Texophoninae, Diactidinae, and Aspidiophoninae constitute tribal elevations and additional new statuses. With a subbasal telopodal prefemoral process, Diactis hedini, n. sp., requires rediagnoses of all three diactidine genera, Diactis Loomis, 1937, and Florea and Caliactis, both by Shelley, 1996, and suggests that telopodal branches ‘B’ in congeners and Florea represent distal relocations of the process along the stem. Similarities in the sizes and shapes of the pleurotergal carinae suggest a sister-group relationship with the other, and partly sympatric, New World family, Abacionidae, which is supported by gonopodal similarities between Colactidinae and Abacion Rafi nesque, 1820. The Western Interior Seaway of the Cretaceous Period, Mesozoic Era, ~141–66 million years ago, appears to have fueled divergence by isolating “proto-abacionid stock” in “Appalachia,” the Eastern North American land mass, which has subsequently spread well into previously inundated areas. The allopatric position of Texophoninae, on the Gulf Coast of south Texas around 1,136 km (710 mi) east of the most proximate familial records, is attributed to this waterway, which eradicated faunal linkages with “proto-Tynommatidae” in “Laramidia,” the Western North American land mass. Texophoninae probably survived the Cretaceous on insular refugia; however, it is rarely encountered anymore and seems destined for imminent extinction. Representatives of the east-Asian families, Caspiopetalidae, Paracortinidae, and Sinocallipodidae, also possess demarcated pleurotergal crests and, implausible though it seems, may share ancestry with the North American taxa vis-à-vis the “Asiamerica” and or “Boreotropic” concepts.
The endemic Floridian milliped genus, Floridobolus Causey, 1957, more closely related to tylobolinines in the western United States (US), Mexico, and Guatemala than syntopic spirobolines, is incorporated into Spirobolidae (Spirobolida: Spirobolidea). With taxonomic priority by one year, its monotypic family is reduced to Floridobolinae, n. stat., comprising Floridobolini and Tylobolini, n. stats., the counterpart to Spirobolinae, comprising Spirobolini and Aztecolini, n. tribe; relationships are Floridobolini + (Tylobolini + (Aztecolini + Spirobolini)). Like F. penneri Causey, 1957, 208 km (130 mi) to the south in the Lake Wales Ridge, Polk and Highlands counties (cos.), F. orini n. sp., inhabits “Big Scrub” environments in the Ocala National Forest, Marion Co. Biogeographic reconstructions, compatible with broader hypotheses on the class’ evolutionary history, indicate that, from a presumptive source area in northern Mexico where the subfamilies overlap, spirobolid stock penetrated the “proto-US” four times, once per tribe, before the Western Interior Seaway developed in the Cretaceous Period, Mesozoic Era. Three expansions headed northeastward into future “Appalachia,” from which taxa spread southward as the Seaway receded. Floridobolini, the fi rst invader, had to be in “proto-Georgia” and positioned to penetrate Florida when the sand dunes that comprise the “Central Highlands” emerged from the sea in the Oligocene (Cenozoic), ~25 mya. As sea levels rose and fell, the dunes fragmented into islands and the subcontinuous Floridobolus population was partitioned. The southernmost became F. penneri; F. orini inhabited a northern island; and a graduate student is investigating other insular remnants for additional species. Shortly after Floridobolini began spreading, Hiltonius/ Tylobolini arose and expanded both southward to Guatemala and northwestward to California; Tylobolus Cook, 1904, diverged in the latter area and dispersed northward to Washington and eastward to Utah/Arizona. The third invader, and the second to disperse northeastward, was Aztecolini, which probably eradicated Floridobolini from some of its established range and was partitioned into Mexican (Aztecolus Chamberlin, 1943) and US (Chicobolus Chamberlin, 1947) taxa by the Seaway. The fi nal invader, Spirobolini, dispersed northwestward and northeastward to both the Pacifi c and Atlantic coasts; instead of Trans-Beringia, we prefer penetration of the Asian part of “Asiamerica,” when it temporarily formed during the Cretaceous, to explain the Mongolian fossil genus, Gobiulus Dzik, 1975, herein assigned to Tylobolini, and the occurrence of Spirobolus Brandt, 1833, in China and Taiwan today. In the east, Narceus Rafi nesque, 1820, spread across Appalachia, eradicated most remaining populations of Floridobolus and Chicobolus, and expanded to Maine and Québec after retreat of the Wisconsin glaciation. Chicobolus and Narceus also penetrated earliest Florida; the former established itself in the Central Highlands, spread through the widening peninsula as sea levels fell, and remained on insular refugia when waters rose. Apparently fueled by the different Floridian environments, Narceus underwent time-consuming speciation; consequently, Floridobolus and Chicobolus still survive on the peninsula, and an allopatric population of the latter inhabits coastal South Carolina. However, N. gordanus (Chamberlin, 1943) occurs syntopically with both in peninsular Florida and may be actively eradicating them from their last stronghold. Trigoniulus niger, takahasii, and segmentatus, all by Takakuwa, 1940, are removed from Spirobolidae and returned toTrigoniulidae (Trigoniulidea). New records in the Appendix include the fi rst of Aztecolus from Durango and Jalisco, Mexico.
A detailed study of the holotype of Sphecomyrma canadensis Wilson, 1985 (Hymenoptera: Formicidae) from Canadian amber has led to the conclusion that the specimen belongs to a new genus, here named Boltonimecia gen.n. Since the taxonomy of stem-group ants is not well understood, in order to find the taxonomic position of this genus, it is necessary to review the classifi cation of stem-group ants in a study of their relation to crown-group ants. In the absence of data for traditional taxonomic approaches, a statistical study was done based on a morphometric analysis of antennae. Scape elongation is believed to play an important role in the evolution of eusociality in ants; however, this hypothesis has never been confirmed statistically. The statistical analysis presented herein lends support to the view that antennal morphology reliably distinguishes stem-group ants from crown-group ants, to determine whether a species belongs to one or the other group. This, in turn, may indicate a relationship exists between eusociality and scape elongation. A review of Cretaceous records of ants is made and the higher classification of Formicidae with definitions of stem and crown groups is proposed. Newly obtained data are discussed focusing particularly on the origin, evolution and diversity of ants.