Research Article |
Corresponding author: Wilson R. Lourenço ( wilson.lourenco@mnhn.fr ) Academic editor: Pavel Stoev
© 2016 Wilson R. Lourenço.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Lourenço WR (2016) A preliminary synopsis on amber scorpions with special reference to Burmite species: an extraordinary development of our knowledge in only 20 years. ZooKeys 600: 75-87. https://doi.org/10.3897/zookeys.600.8913
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A preliminary study on fossil scorpions found in amber, from the Lower Cretaceous through the Palaeocene and up to the Miocene is proposed. Scorpions remain rare among the arthropods found trapped in amber. Only 24 specimens are known from Cretaceous amber, representing eight families and subfamilies, ten genera and 21 species; in parallel, 10 specimens have been recorded from Baltic amber representing seven genera and ten species. A few more recent fossils from Dominican and Mexican amber have also been described. The present study of a new scorpion specimen from the Cretaceous amber of Myanmar (Burmite) resulted in the description of one new species, Betaburmesebuthus bellus sp. n. – belonging to the subfamily Palaeoburmesebuthinae Lourenço, 2015. The new description brings further elements to the clarification of the status of this subfamily, which is now raised to family level. Once again, this new Burmite element attests to the considerable degree of diversity in the Burmese amber-producing forests.
Burmite, Cretaceous, fossil, Myanmar, new species, Palaeoburmesebuthidae , scorpion
Among the fossil arthropods found in amber, scorpions remain extremely rare. The renewal of studies on scorpions trapped in amber began in the early 1980s when a few specimens from Dominican and Mexican amber were described (
Baltic amber was the first to provide fossil scorpions, at the beginning of the 19th century. The first described species was Scorpio schweiggeri (
A second species, Tityus eogenus Menge, 1869, was also described. Unlike Scorpio schweiggeri, Tityus eogenus has received the attention of many authors, first because of its assignment by Menge to a typically Neotropical extant genus, and secondly because the type-specimen was apparently lost soon after its description, which prevented the confirmation of its taxonomic position. Therefore this Baltic amber scorpion has turned into a kind of curiosity. Because of the early disappearance of Menge’s material, for more than one hundred years this Baltic amber fossil has been the subject of discussion and speculation, and was mentioned in a number of publications (e. g.
In 1995, a new specimen of scorpion from Baltic amber was located in Hamburg, Germany. After the examination of all visible characters it was determinated as a member of the family Buthidae, belonging to a new genus and a new species, allied to the genus Lychas C. L. Koch, 1845. Nothing, however, could clearly associate this specimen to the two species previously described by
Even more relevant was the description, in the last 15 years, of 24 specimens from Cretaceous amber, representing eight families and subfamilies, ten genera and 21 species. These fossil scorpions trapped in Cretaceous amber can be dated from 135 to 90 Ma. Although several of these elements can be associated with buthoids, such as Archaeobuthus estephani Lourenço, 2001 (family Archaeobuthidae Lourenço, 2001) from amber of Lebanon and the several species of the genera Palaeoburmesebuthus Lourenço, 2002 and Betaburmesebuthus Lourenço, 2015 (subfamily Palaeoburmesebuthinae Lourenço, 2015) both from Burmite amber from Myanmar (
After the clarification of the familial status of the genus Palaeoburmesebuthus (and consequently of the genus Betaburmesebuthus) and its placement in the subfamily Palaeoburmesebuthinae, this last subfamily was temporarily accommodated in the family Archaeobuthidae Lourenço, 2001, both because of their association to the buthoid lineage, but in particular because of their location in a similar geological horizon. Nevertheless, the recent study of several almost perfectly preserved specimens, clearly attests their relationship to the buthoids (
The exclusion of the family Archaeobuthidae from the buthoids has been proposed by a number of authors (
This new procedure is becoming a common method used by many authors in their attempt to gain credit on the backs of other people’s discoveries. In a few cases only the originally described material has been re-examined, but in many other cases the critics were based solely on the originally published descriptions (see
In the case of Archaeobuthus estephani Lourenço, 2001 (family Archaeobuthidae) all available data are based only on a single but incomplete specimen. The validity of the family Archaeobuthidae was not questioned of itself, but authors such as
In a recent publication, eight authors have described a new fossil scorpion from Chiapas amber (
The specimen investigated here is preserved in very clear block of pale yellow amber. Details of the block are supplied together with the description of the specimen. Many characters, and in particular several trichobothria, are visible in this specimen, allowing detailed investigation. Some characters, however, are not totally observable mainly because the specimen suffered a certain degree of dissection process within the resin. The schematic drawings provided here are interpretations of what was observable. Illustrations and measurements were produced with the aid of a Wild M5 stereomicroscope equipped with a drawing tube and an ocular micrometer. Measurements follow
General morphology shows similarities with several elements of extant buthid scorpions. The following combination of features can be used to diagnose the new family (see also
Palaeoburmesebuthus grimaldii Lourenço, 2002
A juvenile, most certainly a male. Very clear block of pale yellow amber that measured 21.5 × 17.0 × 2 mm. Only a few inclusions and bubbles prevent a 100% observation of all characters. Type locality and horizon: Myanmar (Burma), Kachin; precise locality unknown; Lower Cretaceous.
The specific name is an epythet from Latin “bellus” meaning beautiful, elegant.
The type specimen is deposited in the collection of the Museum of the Geological-Palaeontological Institut of the University of Hamburg (CeNak - Centrum of Natural History), Coll. N° 4586, Coll. Gröhn N° 11086.
General morphology is globally similar with other species of the genus Betaburmesebuthus Lourenço, 2015 and also with extant buthoid scorpions. The following combination of features can be used to diagnose the new species: Carapace weakly to moderately granulated; anterior margin with a moderately marked median concavity. Sternum subpentagonal. Tergites with three carinae, the lateral totally inconspicuous. Sternites with small oval to slit-like spiracle. Metasomal segments I and II with ten carinae; setation on all metasomal segments strongly marked. Fixed and movable fingers of pedipalp chela with a series of small rounded granules and no conspicuous spinoid accessory granules. Trichobothrial pattern with elements ressembling those of extant buthid type A (
Coloration: the scorpion is yellow to slightly reddish-yellow; carapace and tergites yellow; metasomal segments yellow; telson reddish-yellow; pedipalps and legs yellow. Ventral aspect yellow; coxapophysis slightly darker than dorsal aspect.
Carapace weakly granular; anterior margin with a moderately marked median concavity. Carinae inconspicuous; furrows weak. Median ocular tubercle clearly anterior to the centre of carapace; median eyes moderate in size and separated by more than one ocular diameter. Three pairs of lateral eyes of moderate size. Sternum subpentagonal. Mesosomal tergites weakly granular, with one median carina; lateral carinae totally inconspicuous; VII with five weakly marked carinae. Pectines large, with 18-17 teeth; fulcra absent. Sternites weakly granular to smooth, with small oval to slit-like spiracles. Metasomal segment I to IV rounded with 10-10-8-8 carinae; segment V slender with five carinae; dorsal carinae of segments I-IV with minute spinoid granules; dorsal aspect of segments I to V weakly depressed; setation on all segments strongly marked. Telson with a very long pear-shaped vesicle; weakly granular to smooth; aculeus extremely long and moderately curved; setation strongly marked. Cheliceral dentition only partially visible; fixed and movable fingers with one basal tooth observable; distal teeth moderately long (Vachon 1963). Pedipalp femur pentacarinate; patella with 6-7 carinae; internal face of femur and patella with spinoid granules. Chela with weakly marked carinae; all faces not granular, smooth. Fixed and movable fingers each with one series of small rounded granules and no conspicuous spinoid accessory granules; extremity of fingers with stronger spinoid granules; setation of pedipalps weakly marked. Trichobothriotaxy recalling type A (
Morphometric values (in mm) of male juvenile holotype of Betaburmesebuthus bellus sp. n.
Total length 11.80 (including telson). Carapace: length 1.40, anterior width 0.87, posterior width 1.40. Mesosoma length 3.60. Metasomal segments. I: length 0.74, width 0.60; II: length 0.84, width 0.60; III: length 0.94, depth 0.57; IV: length 1.14, depth 0.50; V: length 1.67, depth 0.47. Telson length 1.47. Vesicle: depth 0.37. Pedipalp: femur length 1.14, width 0.34; patella length 1.24, width 0.47; chela length 2.24, width 0.34; movable finger length 1.57.
Betaburmesebuthus bellus sp. n. Male holotype. 5 Chelicera, carapace and tergites I-III, dorsal aspect 6 Sternites V-VII showing carinae and spiracles and metasomal segments I-V and telson, ventro-lateral aspect 7 Ventral aspect, showing Coxapophysis, sternum, genital operculum, pectines and sternites with spiracles. Scale bars: 0.5 mm.
1 | Dorsal trichobothria of pedipalp femur in alpha disposition | Palaeoburmesebuthus- 2 |
– | Dorsal trichobothria of pedipalp femur in beta disposition | Betaburmesebuthus- 3 |
2 | Telson aculeus moderately long and sharp; metasomal segments III-V with moderately marked carinae | P. grimaldii |
– | Telson aculeus extremely long and sharp; metasomal segments III-V with strongly marked carinae | P. ohlhoffi |
3 | Internal face of pedipalp patella without any or to a maximum one spinoid tubercle | 4 |
– | Internal face of pedipalp patella with two or four strong spinoid tubercles | 6 |
4 | Spiracles rounded | 5 |
– | Spiracles slit-like | B. bellus sp. n. |
5 | Pectines with 20-20 teeth | B. kobberti |
– | Pectines with 14-15 teeth | B. muelleri |
6 | Internal face of pedipalp patella with two strong spinoid tubercles; two pairs of lateral eyes | B. bidentatus |
– | Internal face of pedipalp patella with four strong spinoid tubercles; three pairs of lateral eyes | B. fleissneri |
Thanks are due to Carsten Gröhn, Glinde, Germany, for arranging facilities for the study of the described specimen and for allowing the use of several photos of the holotype; to Lucienne Wilmé (Missouri Botanical Garden, Madagascar) and Patrick Waeber (ETH Zurich) for their comments on early versions of the MS; to Lucienne Wilmé for preparing the map; and finally to Elise-Anne Leguin (MNHN, Paris) for assistance with the preparation of plates.