The order Thysanoptera, or thrips (plural and singular), comprises approximately 5,000 known species of small insects with diverse life histories and habits. Most species feed on leaf, stem or flower tissues, though some feed on pollen or fungal hyphae, or are predatory. Some are likely to be significant pollinators (Lewis Reference Lewis1973; Ananthakrishnan Reference Ananthakrishnan1984; Williams Reference Williams2001). Behavioral studies over the last decades have revealed an unexpected diversity of rather sophisticated social behaviour, including even eusociality (Crespi & Mound Reference Crespi, Mound, Choe and Crespi1997; Morris et al. Reference Morris, Mound, Schwarz and Crespi1999).
Thrips comprise a monophyletic group, well defined and easily recognisable, in the case of the winged adults, by narrow, straplike wings with reduced venation, and by the fringe of long setae (“cilia”) surrounding the wing margins. Other synapomorphies of the order include tarsal segments reduced to one or two, with the pretarsus having claws reduced and uniquely possessing a small, eversible bladder (Heming Reference Heming1971). Also, thrips have unusual development, wherein instars I and II are the “larva”, an active, minute, wingless version of the adult typical of hemimetabolous insects. Instars III and IV (in Phlaeothripidae instar V as well) are quiescent and morphologically reduced, the “pupa” (Heming Reference Heming2003).
The structure of thrips mouthparts is unique among insects. Thrips mouthparts comprise a mouthcone consisting of the labrum, labium, a pair of maxillary stipites and laciniae (the latter, so-called “stylets” and another stylet that is a slender left mandible (Reyne Reference Reyne1927; Mickoleit Reference Mickoleit1963; Mound Reference Mound1971; Heming Reference Heming1980, Reference Heming, Shaefer and Leschen1993). Unique to thrips is the loss of the right mandible, rendering the mouthcone asymmetrical. Thrips probe plant, fungal and animal tissues with their slender mouthparts, and suck out fluid contents. The structure and function of these mouthparts suggest they are related to the Hemiptera, but thrips plesiomorphically possess maxillary and labial palps, which all hemipterans have lost. The unusual development of thrips is similar to that of white flies (Aleyrodoidea) and male scale insects (Coccoidea), which may further reflect the close relationship of thrips to Hemiptera. Heming (Reference Heming2003) considered the unusual development in these orders to be convergent, since there are unique features of such in each order.
Thrips appear to be closely related to the extinct psocopteroid family Lophioneuridae, particularly to Zoropsocus Tillyard, Reference Tillyard1935 (Hennig Reference Hennig1981; Zherikhin Reference Zherikhin, Rasnitsyn and Quicke2002). Zherikhin (Reference Zherikhin, Rasnitsyn and Quicke2002) and some others have classified Lophioneuridae as thrips in an order Thripida (=Thysanoptera), with the suborders Lophioneurina and Thripina. Lophioneurids, and particularly Zoropsocus, possessed a reduced venation plesiomorphically similar to that of thrips and at least some are known to have had a narrow (albeit symmetrical) mouthcone (Vishniakova Reference Vishniakova1981). There are eight genera (possibly ten, depending on the classification) from the Permian of Australia, Russia and Kansas (Zherikhin Reference Zherikhin, Rasnitsyn and Quicke2002) and from the Jurassic and Cretaceous of Germany, Russia, China and Australia, including Undacypha Vishniakova, Reference Vishniakova1981, known both from rocks and Taimyr amber. Ansorge (Reference Ansorge1995) synonymised five Late Mesozoic genera under Undacypha. A bizarre genus, Burmacypha Zherikhin, Reference Zherikhin2000, was described from the Cretaceous amber of Myanmar. Besides the symmetrical mouthcone, lophioneurids are plesiomorphic in respect to true thrips in more complete venation, lack of a long marginal fringe on the wings, well-defined orbital sutures, and the unmodified legs. Thus, for this paper we use the traditional, more restricted treatment of Thysanoptera.
The Triassic thrips Triassothrips virginicus Grimaldi & Fraser (Cow Branch Formation: Carnian) and Kazachothrips triassicus Shmakov (Tologoy Formation: Carnian/Norian) were described from the Late Triassic of Virginia and Kazakhstan (Grimaldi et al. Reference Grimaldi, Shmakov and Fraser2004). Jurassic thrips include Liassothrips crassipes (Martynov Reference Martynov1927) and Karataothrips jurassicus Sharov, Reference Sharov1972, both from the Late Jurassic of Kazakhstan (Karabastau Formation: Kimmeridgian). As found recently, Liassothrips may be a branch of primitive Tubulifera showing several specific features in antennae, mouthcone, forelegs and wings (Shmakov Reference Shmakov2008).
By the Early Cretaceous, true thrips became much more abundant. The most diverse Mesozoic thrips occur in Cretaceous ambers, even though the only described ones come from the Early Cretaceous amber from Lebanon (zur Strassen Reference Zur Strassen1973). Bhatti (Reference Bhatti1989) synonymised the families proposed by zur Strassen under the extant family Stenurothripidae, except for Jezzinothripidae zur Strassen, which was placed by Bhatti into the basal extant family Merothripidae. Diverse thrips occur in ambers from the Turonian of New Jersey (Grimaldi et al. Reference Grimaldi, Shedrinsky, Wampler and Grimaldi2000), Aptian of northern Spain (Alonso et al. Reference Alonso, Arillo, Barro, Corral, Grimalt, Lopez, Lopez, Martinez-Delclos, Ortuno, Peñalver and Trinca2000), and in amber of possible Cenomanian age from northern Myanmar (Burma) (Grimaldi et al. Reference Grimaldi, Engel and Nascimbene2002).
In the Early Tertiary, thrips are found in many localities. The fauna of the Late Eocene Baltic amber is the best studied (Bagnall Reference Bagnall1923, Reference Bagnall1924a, Reference Bagnallb; Priesner Reference Priesner1924, Reference Priesner1929; Schliephake Reference Schliephake1990, Reference Schliephake1993, Reference Schliephake1999, Reference Schliephake2000, Reference Schliephake2001, Reference Schliephake2003). Schliephake (Reference Schliephake1997, Reference Schliephake1999, Reference Schliephake2000, Reference Schliephake2001) has also described numerous new species and genera from the Saxonian amber of supposedly the same age. Several taxa have been described also from the late Eocene of the Isle of Wight in the UK (Cockerell Reference Cockerell1917), and from the latest Oligocene of Rott (Schlechtendal Reference Schlechtendal1887) and Enspel (Wedmann Reference Wedmann2000) in Germany. All large living families, such as Aeolothripidae, Thripidae and Phlaeothripidae, are common and diverse there. The Late Tertiary thrips are poorly known. Few taxa are described from the Miocene of California (O'Neil Reference O'Neil1957).
Thirty-two specimens of Thysanoptera were studied from the Insect Limestone of the Isle of Wight, UK. Of these, 19 are identified as members of Recent families Thripidae (six specimens) and Aeolothripidae (13 specimens), and 13 are left unidentified. Three genera are identified in Thripidae and two in Aeolothripidae.
The condition of all specimens is poor: antennae and legs are almost absent; wings are vastly incomplete or absent too. Therefore, all descriptions are not exhaustive.
The insects are preserved in concretions or tabular bands of very fine-grained micrite, known as Insect Limestone. The unit where these concretions/bands occur is known as the Insect Bed, which lies towards the base of the Bembridge Marls Member (Solent Group: Bouldnor Formation).
Gale et al. (Reference Gale, Huggett, Pälike, Laurie, Hailwood and Hardenbol2006) assumed that the Bembridge Marls are earliest Oligocene in age, but Hooker et al. (Reference Hooker, Collinson, Grimes, Sille and Mattey2007, Reference Hooker, Grimes, Mattey, Collinson, Sheldon, Koeberl. and Montanari2009) say that the Insect Limestone is rather latest Eocene (Priabonian) in age, which is followed here.
Most of the specimens at The Natural History Museum, London (NHMUK) belong to the A'Court Smith (purchased 1877, 1883), P.B. Brodie (purchased 1898) and R.W. Hooley (purchased 1924) collections. They are labelled ‘Gurnard Bay’ or ‘Gurnet Bay’ (which is an old name for Gurnard Bay); however, Smith collected specimens all the way from West Cowes to Newtown River on the north-west side of the Isle of Wight. Most of the specimens probably came from Thorness Bay. Brodie and Hooley acquired parts of Smith's collection, so parts and counterparts of individual insects have turned up in all three collections. The parts and counterparts often have different numbers because they were registered at different times. An additional collection was recently discovered at the Sedgwick Museum, Cambridge by A. J. Ross. This collection has also yielded counterparts of specimens at the NHMUK, which indicates that this is another part of the Smith collection. A label with ‘1883’ on it suggests that the Sedgwick Museum acquired this collection in 1883, the same year that the NHMUK purchased specimens from Smith.
Institutional repositories of specimens. NHMUK, Natural History Museum, London; MNEMG, Maidstone Museum & Bentlif Art Gallery, Maidstone; CAMSM, Sedgwick Museum of Earth Sciences, University of Cambridge.
1. Systematic palaeontology
Order Thysanoptera Haliday, Reference Haliday1836
Suborder Terebrantia Haliday, Reference Haliday1836
Family Aeolothripidae Uzel, Reference Uzel1895
Genus Sinaeolothrips Shmakov, gen. nov.
Derivation of name. After genus Aeolothrips. Gender masculine.
Type species. Aeolothrips brodiei Cockerell, Reference Cockerell1917 (by monotypy and present designation).
Diagnosis. Wings are wider than in any other Aeolothripidae, except Aeolothrips, with complete venation including two longitudinal and five cross-veins. Pattern of venation is unique among Aeolothripidae.
Description. Head and prothorax transverse. Pterothorax longitudinal, with slightly rounded sides. All abdominal segments, except the last one, obviously transverse. All cross-veins straight, MCu slightly bent. Fringe is dense and long, about 0·65–0·7 of wing width.
Remarks. The genus is placed into Aeolothripidae because of characteristic venation with seven veins presented. It seems to be related to Aeolothrips; it differs from Aeolothrips by more primitive MCu position. Therefore, Sinaeolothrips might be the ancestor of Aeolothrips, the hypothesis deserving more close study.
Sinaeolothrips brodiei (Cockerell, Reference Cockerell1917)
Text-fig. 1A, B; Plate 1, fig. 1
1917 Aeolothrips brodiei Cockerell, p. 381, fig. 5
Text-figure 1 (A) Sinaeolothrips brodiei (Cockerell Reference Cockerell1917), holotype, NHMUK I.8547, Insect Limestone, Bembridge Marls, Isle of Wight, England; Scale bar=1 mm. (B) Sinaeolothrips brodiei (Cockerell Reference Cockerell1917), NHMUK In.17401, head and prothorax; Scale bar=0.25 mm. (C) Aeolothrips jarzembowskii Shmakov sp. nov., holotype, NHMUK In.25273; Scale bar=1 mm. (D) Coccothrips hoffeinsorum Shmakov sp. nov., holotype, MNEMG 2007.12a [IL 64a]; Scale bar=1 mm.
Plate 1 (1) Sinaeolothrips brodiei (Cockerell Reference Cockerell1917), holotype, NHMUK I.8547, Insect Limestone, Bembridge Marls, Isle of Wight, England. (2) Aeolothrips jarzembowskii Shmakov, sp. nov., holotype, NHMUK In.25273. (3) ? Thrips sp., NHMUK I.9672. (4) Thripidae gen. sp. indet. 1, NHMUK I.9375. Scale bars=1 mm.
Holotype. NHMUK I.8547, Brodie Collection; Insect Limestone, northwest Isle of Wight; headless body with pterothorax poorly preserved and tip of abdomen not visible, with no appendages, other than basally incomplete right forewing.
Other material. NHMUK I.9102, I.9133, I.9536, I.9991, Brodie Collection; NHMUK In.17401, Smith Collection; NHMUK In.24785, II.2855a, b, Hooley Collection; CAMSM X.50140.47b (TN98); all from the Insect Limestone, northwest Isle of Wight.
Description. Bases of veins R, R1, Rs, base of M, MCu and Cu dark coloured. For measurements see Table 1.
Table 1 Measurements and proportions of Sinaeolothrips brodiei (Cockerell, Reference Cockerell1917).
Remarks. Vein coloration varies to an extent, but cross-strips are always absent.
Genus Aeolothrips Haliday, Reference Haliday1836
Aeolothrips jarzembowskii Shmakov, sp. nov.
Text-fig. 1C; Plate 1, fig. 2
Derivation of name. Named after palaeoentomologist Ed Jarzembowski.
Holotype. NHMUK In.25273, Hooley Collection; Insect Limestone, northwest Isle of Wight; almost complete body with head damaged, pterothorax structures not discernible, and abdominal tip invisible, with appendages lost except fore femur, middle leg and both forewings.
Paratypes. NHMUK I.9678, Brodie Collection, NHMUK In.17210, Smith Collection; Insect Limestone, northwest Isle of Wight.
Diagnosis. Forewings bearing two cross-colour strips, proximal one pale, incomplete, reaching wing fore margin; distal one complete, more distinct and broad, reaching both wing margins by bulges, with narrow spot near its middle.
Description. Head slightly transverse, prothorax highly transverse, pterothorax longitudinal, with obviously rounded sides. All abdominal segments except for last one strongly transverse. All cross-veins straight. Fringe wide, c.0·81–0·83 mm, as long as wing width. For measurements, see Table 2.
Table 2 Measurements and proportions of Aeolothrips jarzembowskii Shmakov, sp. nov.
Remarks. Venation is typical of the genus, but the shape of wing cross-strips is apparently unknown in other congeners. On several wings, for example on left holotype forewing, distal strip is much paler between Rs and M, but distinct outside this section.
Family Thripidae Stephens, Reference Stephens1829
Subfamily Panchaetothripinae Bagnall, Reference Bagnall1912
Genus Coccothrips Shmakov, gen. nov.
Derivation of name. After alternating wing wrinkles, similar to these on wings of the extant family Matsucoccidae (Hemiptera: Coccoidea).
Type species. Coccothrips hoffeinsorum Shmakov, sp.nov.
Diagnosis. Wings bear single central longitudinal vein, which reach tip of wings. Forewings covered by regular alternate wrinkles before and after the vein. Forewings are broad, lancet-like with weakly rounded tips. Hindwings are much narrower than forewings, without wrinkles.
Description. Prothorax and pterothorax transverse, with straight sides. Abdominal segments I–VII obviously transverse. Wing marginal setae are long even on front margin, but not dense at front margin of forewing, without cross-setae on all wings.
Remarks. Most of diagnostic features, such as alternate wrinkles, shape of forewing and its great width with single vein only, are very uncommon for all thrips families. The species in question was placed into Thysanoptera because of the wings with single vein and marginal fringe. Such highly reduced venation is frequent for family Thripidae, in which all members of subfamily Panchaetothripinae have socketed wings and dorsal body surface.
Coccothrips hoffeinsorum Shmakov, sp. nov.
Text-fig. 1D; Plate 2, figs 1–4
Plate 2 (1) Coccothrips hoffeinsorum Shmakov, sp. nov., holotype, MNEMG 2007.12a [IL 64a], Jarzembowski collection, Insect Limestone, Bembridge Marls, Isle of Wight, England. (2) Coccothrips hoffeinsorum Shmakov, sp. nov., holotype, MNEMG 2007.12b [IL 64b], Jarzembowski collection. (3) Coccothrips hoffeinsorum Shmakov, sp. nov., NHMUK In.43474a, Hooley Collection. (4) Coccothrips hoffeinsorum Shmakov, sp. nov., NHMUK In.43474b, Hooley Collection. Scale bars=1 mm.
Derivation of name. Named after Christel and Hans Hoffeins.
Holotype. MNEMG 2007.12a, b [IL 64a, b] Jarzembowski coll.; Insect Limestone, northwest Isle of Wight; body without head, with abdomen and prothorax damaged, pterothoracic structures discernible, with both hind legs incomplete, without tarsi. Forewings and one hindwing present; one forewing is almost complete, hindwing without apical part.
Paratype. NHMUK In.43474a, b, Hooley Collection; Insect Limestone, northwest Isle of Wight.
Description. All wings dark coloured, but there are more or less light strips at forewings following wrinkles from wing base even to tip. For measurements, see Table 3.
Table 3 Measurements and proportions of Coccothrips hoffeinsorum Shmakov, sp. nov.
Remarks. Wings of NHMUK specimen are much less coloured than wings of MNEMG one; it may be caused by preservation or intraspecific variation.
Subfamily Thripinae Karny, Reference Karny1921
Genus Thrips Linnaeus, Reference Linnaeus1758
?Thrips sp.
Plate 1, fig. 3
Material. NHMUK I.9349, I.9672, Brodie Collection; Insect Limestone, northwest Isle of Wight; almost complete body with legs and partial wings, with venation not visible.
Description. For measurements, see Table 4.
Table 4 Measurements and proportions of ?Thrips sp.
Remarks. Attribution to Thrips is based on the characteristic shape of head front surface between obvious prominent eyes and absence of any rugged sculpture on thorax and abdomen. Further identification is impossible at present because of the incomplete preservation of the material available.
Thripidae gen. sp. indet. 1
Plate 1, fig. 4
Material. NHMUK In.25324, II.2854, Hooley Collection; NHMUK I.9375, Brodie Collection; all from the Insect Limestone, northwest Isle of Wight; all with no preserved head, legs or hind wings; pterothorax structures are not visible; all fore wings are incomplete at width, but one wing of NHMUK II.2854 is almost complete at length.
Description. For measurements, see Table 5.
Table 5 Measurments and proportions of Thripidae gen. sp. indet. 1.
Remarks. Specimens are determined as Thripidae, because of their narrow wings with reduced venation. They are placed in one group because of same size.
Thripidae gen. sp. indet. 2
Material. NHMUK I.10262, Brodie Collection; Insect Limestone, northwest Isle of Wight; deformed (much compressed) body with fore leg and partial forewing.
Description. Medial section of forewing highly pigmented, bearing light spots at wing midwidth. For measurements, see Table 6.
Table 6 Measurements and proportions of Thripidae gen. sp. indet. 2.
Remarks. Specimen is determined as Thripidae, because of its narrow wings with reduced venation.
2. Discussion
Aeolothrips is a worldwide predatory genus, preying on various phytophagous thrips, including Thrips species, also found in the Insect Limestone.
The identification of the genus Thrips is not certain because of the incomplete preservation: antennae and chaetotaxy are never seen; wings and thoracic structures are poorly preserved. The genus Thrips is phytophagous, mainly on herbaceous plants but sometimes on trees as well. It has a world-wide distribution, including subarctic and desert areas. The developmental optimum of the genus lies around 25°C (Ghabn Reference Ghabn1948; Priesner Reference Priesner1960). Populations developing at higher temperatures are paler and smaller, and macropterous forms predominate; low temperatures have the reverse effect (Gentile & Bailey Reference Gentile and Bailey1968). The fossils at hand are of more or less normal size and pigmentation, so providing the identification is correct, and given the mean duration of active ontogenesis (except egg stage) taking some 15–20 days, this makes it possible to hypothesise the environment with the temperature c. 25°C lasting for at least 15–20 days a year.
3. Acknowledgements
The author gratefully acknowledges all members of the Arthropoda laboratory for their useful comments, and Dr. A. P. Rasnitsyn for help in producing this manuscript. I thank INTAS for financial support. This paper contributes to INTAS Project No. 03-51-4367. Also I acknowledge the project coordinator A. J. Ross and the NHMUK photographer, Phil Crabb, for taking the pictures for Plates 1 (fig. 1) and 2 (figs 1–4).
