Alba Sánchez-García

A rich and diverse tanaidomorphan (Crustacea: Tanaidacea) assemblage associated with Early Cretaceous resin-producing forests in North Iberia: palaeobiological implications

The extinct tanaidomorphan diversity from Early Cretaceous Spanish amber, currently comprising 26 specimens, is reassessed. The fossil family Alavatanaidae Vonk & Schram, 2007, described from Spanish amber, is revised on account of new preparation of type specimens and the discovery of new material. The described tanaidomorphan taxa are classified within the superfamily Paratanaoidea. An emended diagnosis for Alavatanaidae is provided, as well as for the genera Alavatanais Vonk & Schram, 2007 and Proleptochelia Vonk & Schram, 2007, and their respective species Alavatanais carabe Vonk & Schram, 2007 and Proleptochelia tenuissima Vonk & Schram, 2007. Three new species, two of them classified in a new genus each, are described: Alavatanais margulisae Sánchez-García, Peñalver & Delclòs sp. nov., Eurotanais terminator Sánchez-García, Peñalver & Delclòs gen. et sp. nov. and Electrotanais monolithus Sánchez-García, Peñalver & Delclòs gen. et sp. nov. Proleptochelia euskadiensis Vonk & Schram, 2007 is considered a junior synonym of A. carabe, and the genus Proleptochelia, together with its type and only species P. tenuissima, is left without familial placement within Paratanaoidea. Within this superfamily, Alavatanaidae is closely related to Leptocheliidae. Also, morphological variability due to sexual dimorphism in the studied paratanaoids has been determined. Multiple lines of taphonomic and palaeobiological evidence indicate that the Spanish amber tanaids were most likely inhabitants of wet or moist forest floors. http://zoobank.org/urn:lsid:zoobank.org:pub:DC943B18-A01C-412C-8378-C644FEFDA716

Springtails from the Early Cretaceous Amber of Spain (Collembola: Entomobryomorpha), with an Annotated Checklist of Fossil Collembola

ABSTRACT Entomobryomorphan springtails (Hexapoda: Entognatha: Collembola) of the family Isotomidae are the most numerous group of Collembola in Spanish amber, a pattern typical in other studied Cretaceous amber deposits. Here we provide a revision of the Spanish amber springtail fauna, Early Cretaceous (Late Albian) in age, based on 93 specimens sufficiently well preserved to permit specific identification. Three new species are erected within the Isotomidae: Anurophorinae. These are: Burmisotoma spinulifera, new species, Protoisotoma autrigoniensis, new species, and Proisotoma communis, new species. The two former are respectively placed in the Cretaceous genera Burmisotoma Christiansen and Nascimbene (previously known from Cenomanian Burmese amber) and Protoisotoma Christiansen and Pike (in both Burmese and Canadian ambers), while the last species is indistinguishable from the extant, cosmopolitan genus Proisotoma Börner (also recorded in Burmese amber). Low morphological intraspecific variability is described for P. communis. Taxa are discussed in relation to other fossil entomobryomorphan lineages as well as their modern counterparts. A catalog of the known fossil springtails is appended. Isotomidae are diverse springtails, putatively basal among Entomobryomorpha and extending back into the Early Devonian. Indeed, taxa described herein are overall remarkably similar to their extant relatives, emphasizing the antiquity and morphological stasis of the group as a whole.

Long-term stasis in a diverse fauna of Early Cretaceous springtails (Collembola: Symphypleona)

Springtails (Hexapoda: Entognatha: Collembola) extend into at least the Early Devonian, but have a meagre record as fossils until the latter part of the Mesozoic. Here, we document a diverse fauna of springtails in the order Symphypleona from amber recovered at the Peñacerrada I locality, Moraza, northern Spain, and from the Late Albian Utrillas Group in the Basque-Cantabrian Basin. The fauna includes representatives of all of the principal suborders and infraorders, and most superfamilies, of the Symphypleona. This revision of the fauna includes the discovery and description of five new genera and species scattered across the phylogenetic diversity of the clade: Pseudosminthurides stoechus gen. et sp. nov. (Sminthurididae), Cretokatianna bucculenta gen. et sp. nov. (Katiannidae), Sphyrotheciscus senectus gen. et sp. nov. (Sminthuridae: Sphyrothecinae), Archeallacma dolichopoda gen. et sp. nov. (Sminthuridae: Sminthurinae?) and the enigmatic Katiannasminthurus xenopygus gen. et sp. nov. (Sminthuridae? incertae sedis). This is the earliest amber fauna of springtails yet described, and highlights the remarkably modern character of the group even during the early stages of the Cretaceous. http://zoobank.org/urn:lsid:zoobank.org:pub:BFF73D0D-31A0-4AE1-9CA4-C62424177C7D

Mating and aggregative behaviors among basal hexapods in the Early Cretaceous

Among the many challenges in paleobiology is the inference and reconstruction of behaviors that rarely, if ever, leave a physical trace on the environment that is suitable for fossilization. Of particular significance are those behaviors tied to mating and courtship, individual interactions critical for species integrity and continuance, as well as those for dispersal, permitting the taxon to expand its distribution as well as access new habitats in the face of local or long-term environmental change. In this context, two recently discovered fossils from the Early Cretaceous amber of Spain (ca. 105 mya) give a detailed view of otherwise fleeting ethologies in Collembola. These occurrences are phylogenetically spaced across the class, and from species representing the two major clades of springtails—Symphypleona and Entomobryomorpha. Specifically, we report unique evidence from a symphypleonan male (Pseudosminthurides stoechus Sánchez-García & Engel, 2016) with modified antennae that may have functioned as a clasping organ for securing females during mating on water’s surface, and from an aggregation of entomobryomorphan individuals (Proisotoma communis Sánchez-García & Engel, 2016) purportedly representing a swarming episode on the forest floor. We demonstrate that the mating behavioral repertoire in P. stoechus, which is associated with considerable morphological adaptations, likely implied elaborate courtship and maneuvering for guarantee sperm transfer in an epineustic species. These discoveries reveal significant behaviors consistent with modern counterparts and a generalized stasis for some ancient hexapod ethologies associated with complex mating and courtship and social or pre-social aggregations, so critical to specific constancy and dispersal.

Marsupial brood care in Cretaceous tanaidaceans

Parental care in animal evolution has long fascinated biologists, but tracing this complex of behavioural repertoires is challenging, as these transitory states often leave no corporeal traces as fossils. Among modern invertebrates, the tanaidaceans (Malacostraca: Peracarida), a lineage of marsupial crustaceans, show an interesting variety of brooding strategies. Here we report on fossil tanaidaceans from the Cretaceous of Spain and France that provide conclusive evidence for marsupial care of brood-offspring. Two exceptionally preserved female specimens of Alavatanais carabe and A. margulisae from Late Albian Peñacerrada I amber (Spain) possess four pairs of rudimentary oostegites, indicating formation of a marsupium. From Recent data, given the taxonomic distribution of a marsupium of four pairs of oostegites, we hypothesize that this may be plesiomorphic for the Tanaidomorpha. We also report on a peculiar tanaidacean specimen referable to the fossil family Alavatanaidae, Daenerytanais maieuticus gen. et sp. nov., from Early Cenomanian La Buzinie amber (France), preserved with its marsupial pouch and content. Our discoveries provide early evidence of the peracarid reproductive strategy, as seen in modern Tanaidacea, and argue that this form of parental care may have played a role in the diversification of the lineage during this period.

The semi-aquatic pondweed bugs of a Cretaceous swamp

Pondweed bugs (Hemiptera: Mesoveliidae), considered a sister group to all other Gerromorpha, are exceedingly rare as fossils. Therefore, each new discovery of a fossil mesoveliid is of high interest, giving new insight into their early evolutionary history and diversity and enabling the testing of their proposed relationships. Here, we report the discovery of new mesoveliid material from Spanish Lower Cretaceous (Albian) amber, which is the first such find in Spanish amber. To date, fossil records of this family only include one species from French Kimmeridgian as compression fossils, two species in French amber (Albian-Cenomanian boundary), and one in Dominican amber (Miocene). The discovery of two males and one female described and figured as Glaesivelia pulcherrima Sánchez-García & Solórzano Kraemer gen. et sp. n., and a single female described and figured as Iberovelia quisquilia Sánchez-García & Nel, gen. et sp. n., reveals novel combinations of traits related to some genera currently in the subfamily Mesoveliinae. Brief comments about challenges facing the study of fossil mesoveliids are provided, showing the necessity for a revision of the existing phylogenetic hypotheses. Some of the specimens were studied using infrared microscopy, a promising alternative to the systematic study of organisms preserved in amber that cannot be clearly visualised. The new taxa significantly expand the fossil record of the family and shed new light on its palaeoecology. The fossils indicate that Mesoveliidae were certainly diverse by the Cretaceous and that numerous tiny cryptic species living in humid terrestrial to marginal aquatic habitats remain to be discovered. Furthermore, the finding of several specimens as syninclusions suggests aggregative behaviour, thereby representing the earliest documented evidence of such ethology.