Corresponding author: Ricardo Pérez-de la Fuente (
Academic editor: A. Contreras-Ramos
The Albian amber from Spain presently harbors the greatest number and diversity of amber adult fossil snakeflies (
Raphidioptera (snakeflies) are regarded as one of the most primitive lineages of holometabolous insects, their fossil record dating back to the Early Jurassic (
Raphidioptera currently comprises six families, i.e., four extinct families,
Distribution of the Early Cretaceous snakeflies currently classified within the
Currently recognized genera classified within the extinct families
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§ Genus |
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§ Recently transferred from
Cretaceous amber snakeflies (
Age, taxa | Amber locality (country) |
---|---|
Neocomian (Barremian–Aptian) | |
Jezzine (Lebanon) | |
Jezzine (Lebanon) | |
Albian | |
Peñacerrada I (Spain) | |
Peñacerrada I (Spain) | |
Peñacerrada I (Spain) | |
Mesoraphidiid gen. et sp. indet. 1 (MCNA 9218) | Peñacerrada I (Spain) |
Mesoraphidiid gen. et sp. indet. 3 (MCNA 9316) | Peñacerrada I (Spain) |
El Soplao (Spain) | |
El Soplao (Spain) | |
El Soplao (Spain) | |
Mesoraphidiid gen. et sp. indet. 2 (CES 376) | El Soplao (Spain) |
Hukwang (Myanmar) | |
Mesoraphidiid larva 1 (in |
Hukwang (Myanmar) |
Mesoraphidiid larva 2 (in |
Hukwang (Myanmar) |
Mesoraphidiid larva 3 (in |
Hukwang (Myanmar) |
Late Albian | |
Mesoraphidiid larva (in |
Archingeay-Les Nouillers (France) |
Turonian | |
New Jersey (USA) | |
Mesoraphidiid larva (in |
New Jersey (USA) |
Campanian | |
Mesoraphidiid larva (in |
Grassy Lake (Canada) |
The recent discovery of a significant paleodiversity of snakeflies in Spanish amber stimulated the present work. Herein we describe this diversity and place it in the context of other Mesozoic snakeflies, highlighting some factors that could explain the uniqueness of this record when compared to other Cretaceous ambers.
Samples designated by the institutional abbreviation CES are housed in the laboratory of the El Soplao Cave, Celis, Cantabria (Spain) encompassing the Institutional Collection from the El Soplao outcrop; whereas those designated as MCNA are housed in the Museo de Ciencias Naturales de Álava, Vitoria-Gasteiz, Spain. The higher classification followed herein is modified from that of
Drawings were prepared with a camera lucida attached to an Olympus BX51 microscope. Photomicrographs were prepared using a Nikon D1x digital camera attached to an Infinity K-2 long-distance microscopic lens. Images were merged using Combine ZP and Helicon Focus 4.2.1 (HeliconSoft Ltd.) softwares. All measurements are in millimeters and were taken using an ocular graticule.
Abbreviations. Veins: A, anal; C, costa; CuA, cubital anterior; CuP, cubital posterior; MA, medial anterior; MP, medial posterior; ptc, pterostigmal crossvein; R, radial; Rs, radial sector; Sc, subcosta. Wing fields (in italics):
The Peñacerrada I (in Moraza, Burgos.
The amber localities are Albian in age, about 110 Mya (
From Peñacerrada I two different vegetational assemblages were distinguished in palynological analyses (
Different tree groups have been interpreted as the resin producers. For the oriental area of the BCB (Peñacerrada I), araucariaceans close to the Recent genus
MCNA 12068.4, from Peñacerrada I amber; fore- and hind wing distal fragments. Three associated hymenopterans are preserved as syninclusions.
Fore- and hind wing with a relatively long pterostigma with a strongly oblique and slightly sinusoid pterostigmal crossvein placed beyond pterostigmal midlength; fore- and hind wing with one closed radial cell distal to pterostigma; forewing Rs with six branches; forewing with at least eight closed subradial cells.
Sex unknown. Veins with some strong, very short setae preserved, membrane hyaline.
Drawings of
The specific epithet is a combination of the Greek words
Within the current taxonomic framework, the numerous crossveins of MCNA 12068.4 are indicative of placement in the
The specimen is tentatively classified within the genus
Small size; costal field very broad; pterostigma with a single, subdistal, strongly oblique, slightly sinuose to arcuate crossvein; pterostigma with a diffuse base; forewing with Rs and MA each forked twice; forewing with second radial cell proximally broad.
The new genus-group name is a combination of the Greek word
CES 391.1, from El Soplao amber; incomplete specimen, almost complete left fore- and hind wings (lacking their basalmost part), distal half of right hind wing and apex of right forewing, partial abdomen, and two leg fragments. Dense fungal hyphae infestate the abdomen and wings. The specimen is preserved together with the following syninclusions: two coleopterans, two hymenopterans (one of them, CES 391.2, belonging to the
As for the genus (
Sex unknown.Legs patterned as follows (at least in the preserved fragments): femur with three dark areas, tibia with proximal area darkened and a dark area beyond midlength.Wing veins brown; veins with strong, very short setae, especially abundant on C; membrane hyaline.
Drawings of
The specific epithet is the Latin term
MCNA 9343, from Peñacerrada I amber; hind wing fragment and abdominal apex, including the genitalia.
The new species is similar to
Male.
The specific epithet refers to the occurrence of this species in ancient Spain (
Although the base of the pterostigma is not preserved and it is accordingly impossible to ascertain if it was diffuse (i.e., lacking a crossvein), this species is tentatively placed in the genus
Minute size. Head ovoid, with the portion posterior to the compound eyes longer than the eye diameter and tapering caudad; three large ocelli present, situated between anterior half of compound eyes; antennae with a low number of flagellomeres (i.e., ≤ 26). Pronotum slightly longer than head, with a constant height along its entire length. Mesotibiae especially swollen; process at midlength of the metatibiae absent. Forewing with costal field moderately broad; pterostigma elongate, without crossveins; Sc terminating into C slightly distad wing midlength; six c-sc crossveins present; two discoidal cells posterior to MP; apicalmost branch of CuA simple; 1cua-cup crossvein located at the M-CuA separation.
The new genus-group name is a combination of the Greek term
In addition to the aforementioned taxa, five mesoraphidiids with minute size have been hitherto described from compression fossils:
CES 364.1, from El Soplao amber; almost complete female, just lacking the distalmost portion of both forewings beyond the end of the pterostigma and the distal third of the right hind wing. The first left leg is disarticulated. The specimen is preserved together with the following syninclusions: one evaniid (a new
As for the genus (
Female.Integument dark brown; legs patterned as follows: femora darkened from just before their midlength to their end; three dark areas on tibiae, proximally, medially and distally; tarsomere 1 not darkened, distal tarsomeres darkened.
Drawings of
In the Cantabrian mythology, the “ventolines” are tenacious and always cheerful fairy-like air beings that dwell in the depths of the sky and, when summoned, help defenseless fishermen by placidly steering their boats to the shore while embracing them with their warm green wings. The term has been singularized and feminized for combination.
In extant snakeflies, the dense annulations of the ovipositor (cf.
Minute size. Head rhomboidal, with clypeus especially elongate and the portion posterior to the compound eyes shorter than the eye diameter and strongly tapering caudad; three large ocelli present, situated near the posterior tangent of compound eyes; antennae extremely elongate, with a high number of flagellomeres (i.e., ≥ 38). Pronotum shorter than head, with a constant height along its entire length. All tibiae especially swollen medio-apically; process at midlength of the metatibia indistinct. Bilobed extensions of third tarsomeres with distal digitiform processes.
The new genus-group name is a combination of Álava, from Álava amber (the name of the group for Peñacerrada I and Peñacerrada II amber localities), and
Although most of the wings are not preserved, the other features of
MCNA 13608, from Peñacerrada I amber; partial specimen showing head and ventral parts of thorax and abdomen, including the ovipositor. Only the basalmost part of the wings is preserved.
As for the genus (
Female.Body length excluding ovipositor 5.7. Integument dark brown; legs patterned as follows: femora darkened from just before their midlength to their end; two dark regions on tibiae, proximally and distally (medial dark region absent); tarsomere 1 not darkened, distal tarsomeres darkened.
Drawing of
The specific epithet is the Latin term
According to the original diagnosis, this monospecific genus was characterized by the following combination of characters: minute size (forewing length 5.5). Head more or less quadrangular; with portion posterior to the compound eyes slightly shorter than the eye diameter and not tapering caudad; three large ocelli present, situated between anterior half of the compound eyes; posterior border of head with a distinct collar-like lip. Pronotum subequal in length to head length, with anterior half narrowed dorsoventrally relative to posterior half (i.e., with slight downward curve in lateral view). Process present at midlength of the metatibiae in a posterior position. Forewing with costal field relatively broad (at widest point costal field as broad as pterostigma); pterostigma elongate, without crossveins; Sc terminating into C in distal two-thirds of wing length; four c-sc crossveins; two discoidal cells posterior to MP; 1cua-cup crossvein strongly basad M-CuA separation; posterior branch of MP forked. Refer to
MCNA 9218, from Peñacerrada I amber; wing apex plus two minute wing fragments lacking formal descriptive significance. The sample consists of part and counterpart after the amber piece broke following the plane of the inclusion.
Sex unknown.
The present material is distinct from other Spanish amber snakeflies but does not preserve enough detail to permit formal designation as a taxonomic entity. The presence of a pterostigmal crossvein immediately discounts
Fragmentary wing remains, genus and species indeterminate: CES 9218 part and counterpart (
Drawings of fragmentary wing remains, genus and species indeterminate: CES 9218 counterpart (A), CES 376 (B), and MCNA 9316 (C–D).
CES 376, from El Soplao amber; forewing apex and the area surrounding pterostigma from an additional wing. Some additional dorsoproximal parts of the wing are also present but with a very poor preservation, so just a few more characters can be elucidated. An indeterminate hymenopteran is present as a syninclusion.
Length as preserved ca. 5.0 (wing well preserved only in 3.4 of that length), maximum width as preserved 2.7; wing apex pointed, positioned within Rs series; wing veins brown, meeting wing margins without bifurcating; veins with strong, short setae, especially abundant on C; Sc ending and proximal r-rs crossvein (1r-rs?; very faintly preserved) situated at about same wing length, pterostigma slightly widening distally, infumate; pterostigma with a very faint subdistal, rather straight (not conspicuously arcuate), strongly oblique crossvein; uncertain if pterostigmal division present; apical branches of Rs, MA and MP subparallel; two apical branches of R distal to pterostigma; Rs with four branches, posteriormost originating before distalmost r-rs crossvein (2r-rs?), separated from it by much more than its length; rs-ma and distalmost ma-mp crossveins lacking in preserved wing fragment, so most likely with a proximal position; MA most likely with three branches.
Despite the fact that CES 376 is distinct from the other taxa in Spanish amber, it is not named as its preserved parts are not enough to resolve its affinities. The wing fragments show a high resemblance with some mesoraphidiids such as
MCNA 9316, from Peñacerrada I amber; fore- and hind wing fragments from the same side of the body and a poorly preserved part of the abdomen, although the genitalia is somewhat visible. The amber piece contains abundant organic remains. The specimen is preserved together with legs of a spider as syninclusions.
Male.Small size (inferred from preserved wing fragments).
The following keys include only those species sufficiently diagnostic to name. As such, the additional morphospecies are not considered here and so all new material should be cross-referenced with the above accounts on those more fragmentarily known taxa. Note that
1 | Fore-/hind wing with pterostigmal crossvein | 2 |
– | Fore-/hind wing without pterostigmal crossvein ( |
4 |
2 | Fore-/hind wing with sparse or moderate crossvenation; at most with two radial cells, three medial cells, and three discoidal cells posterior to MP; often with no closed subradial cells (i.e., cells between Rs branches) ( |
3 |
– | Fore-/hind wing with relatively rich crossvenation; with at least three radial cells, and numerous subradial, medial, and discoidal cells posterior to MP ( |
|
3 | Fore-/hind wing with a single pterostigmal crossvein; distalmost r-rs crossvein meeting R within pterostigma, Rs (proximally) forking before distalmost r-rs; rs-ma crossvein meeting MA before its distalmost fork | |
– | Hind wing with two pterostigmal crossveins; distalmost r-rs crossvein meeting R beyond pterostigma, Rs forking at r-rs crossvein; rs-ma crossvein meeting MA after its distalmost fork | |
4 | Forewing with four c-sc crossveins; apicalmost branch of CuA forked near wing margin; M-CuA separation between 1cua-cup and 2cua-cup crossveins (closer to latter) | |
– | Forewing with six c-sc crossveins; apicalmost branch of CuA unforked; M-CuA separation at the 1cua-cup crossvein |
1 | Head not rhomboidal; compound eyes shorter, equal, or not much longer than head posterior to eyes; antennae with a low number of flagellomeres (≤ 26) | 2 |
– | Head rhomboidal; compound eyes longer than head posterior to eyes; antennae very elongate, with a high number of flagellomeres (≥ 38) | 5 |
2 | Head ovoid; compound eyes shorter or equal than head posterior to eyes; antennae with less than 26 flagellomeres | 3 |
– | Head quadrangular; compound eyes slightly longer than head posterior to eyes;antennae with 26 flagellomeres | |
3 | Compound eyes not distinctly shorter than head posterior to eyes; ocelli positioned between posterior half of compound eyes | 4 |
– | Compound eyes distinctly shorter than head posterior to eyes; ocelli positioned between anterior half of compound eyes | |
4 | Compound eyes nearly equal than head posterior to eyes; antennae longer than head length; posterior border of head without a collar-like lip | |
– | Compound eyes apparently slightly longer or equal than head posterior to eyes; antennae shorter than head length; posterior border of head with a collar-like lip | |
5 | Compound eyes two times head posterior to eyes; clypeus short; antennae with around 38 flagellomeres; pronotum longer than head; bilobed extensions of third tarsomere lacking digitiform processes | |
– | Compound eyes ca. 1.4 times head posterior to eyes; clypeus especially elongate; antennae with more than 38 flagellomeres; pronotum shorter than head; bilobed extensions of third tarsomere with distal digitiform processes |
Recently,
Seven larval mesoraphidiids have been described up to now from five Cretaceous amber localities around the world (
Like many moderate- to large-sized insects, snakeflies are difficult to find as amber inclusions, particularly complete specimens in Cretaceous ambers. It is not surprising that those individuals recovered as complete, or relatively complete, inclusions are among the smallest members of the order. Nonetheless, immatures and fragments of much larger snakefly species are also found as amber inclusions as evidenced by the rich Spanish fauna. What is more curious is that among the more abundant Cretaceous amber sources such as Lebanon, Myanmar, New Jersey, and Canada, the reported snakeflies remain relative rarities (
However, another hypothesis could explain the high abundance/diversity of snakeflies in Spanish amber, apart from its insularity. Perhaps this abundance is partly owing to the common occurrence of wildfires in the Spanish amber environment, inferred from evidence at several Spanish amber localities (see
The discovery of the first amber baissopterid is especially remarkable. Furthermore, the presence of the family in the Iberian territory during the Early Cretaceous completes the remarkable preexisting paleogeographic baissopterid hiatus between the Cretaceous localities from eastern Asia and Brazil.
With the fossils herein described, the Albian amber of Spain currently harbors the greatest abundance and diversity of snakeflies in Cretaceous resins. As is also suggested by other paleoentolomological records, this significant snakefly paleodiversity may reflect a faunistic singularity of the Iberian territory during the Albian perhaps as a consequence of its geographic isolation during the Jurassic and the Cretaceous, or a combination of this with an environment resulting from episodic wildfires. Wildfires would have increased the availability of dead wood as a substrate for the xylophagous or xylophilous insects to develop, which, in turn, could have aided the increase in the xylophilous, predatory snakefly populations.
We thank the Museo de Ciencias Naturales de Álava for providing samples from the Peñacerrada I outcrop, and the staff from El Soplao Cave and the Instituto Geológico y Minero de España (IGME) for providing samples from the El Soplao outcrop. The authors are indebted to R. López-del Valle for the preparation of the samples, and to two anonymous reviewers for their helpful comments. This paper is part of the first author’s doctoral dissertation, supported by an APIF grant from the University of Barcelona. This work is a contribution to the projects CGL2008-00550/BTE and CGL2011-23948/BTE, together as “The Cretaceous amber of Spain: A multidisciplinary study”, of the Spanish Ministry of Economy and Competitivity, and the IGME project 491-CANOA 35015 “Investigación científica y técnica de la Cueva de El Soplao y su entorno geológico” (to EP). This is also a contribution of the Division of Entomology, University of Kansas Natural History Museum, partial support for which was provided by US National Science Foundation grant DEB-0542909 (to MSE).