The genus Microananteris Lourenço, 2003 in French Guiana (Scorpiones: Buthidae)

ABSTRACT Two new humicolous micro-buthid species belonging to the genus Microananteris Lourenço, 2003 are described from French Guiana. The descriptions are based on two adult specimens collected in organic soil with the use of extraction by the Berlese method. The new discoveries bring further support to the validity of the genus Microananteris. The geographic distribution of the known species of Microananteris remains limited to the only territory of French Guiana.


INTRODUCTION
As already outlined in previous papers, humicolous scorpions are globally rare (Lourenço 2003(Lourenço , 2005(Lourenço , 2009) and new discoveries remain rather confidential (Lourenço et al. 2019). The first instance to be precisely reported was that of Akentrobuthus leleupi Lamoral, 1976, a buthid scorpion found in forests of the Kivu Province in Congo (Lamoral 1976). Just before this latter publication (Lamoral 1976), Vachon (1974) described a new genus and species, Lycha sioides amieti Vachon, 1974 from the forest of Otomoto in the Cameroon. According to the collector of this species, J. L. Amiet, the studied specimens were exclusively found in organic soil. Therefore, it was subsequently classified as humicolous (Vachon, in litt.). In more recent years a new genus of truly humicolous buthid scorpions, Microcharmus Lourenço, 1995 was described from Madagascar (Lourenço 1995). In the following years a second genus and several new species were discovered confirming the usefulness of accommodating microcharmids in their own family Microcharmidae Lourenço, 1996. For a global synopsis refer to Lourenço et al. (2019).
Known examples of humicolous buthid species belonging to the subfamily Ananterinae (sensu Pocock 1900) or to the "Ananteris group" as suggested by Lourenço (2011) are more informative concerning the possible evolution of genera, such as Ananteris Thorell, 1891 andMicroananteris Lourenço, 2003, from (Lourenço 2003(Lourenço , 2005(Lourenço , 2012. The morphological traits of Ananteris Thorell, 1891 and Microananteris demonstrate their relationships. The species are small in size and show the persistence of neotenic structures in the adults. In most instances, they show cryptozoic behaviour and a number of species are humicolous. Their ecology and general biology is poorly known, but detailed inventories carried out during the last 45 years, demonstrate that the total number of species is significantly greater than what was initially expected (Lourenço & Motta 2019); most, however remain extremely rare and show very limited and patchy ranges of distribution.
Another characteristic observed for several species of the genus Ananteris is the rarity of juvenile forms collected with the classical sampling methods such as overturning rocks, the use of ultraviolet light and pitfall traps. Only the use of extraction methods, such as these of Berlese, Winkler and Kempson, has resulted in more frequent collections of juvenile forms, and also led to the discovery and description of new humicolous species.
The genus Microananteris was described on the basis of a single adult female collected in the Central region of French Guiana in an area of dense humid forest with the use of extraction by Berlese Method (Lourenço 2003). The validity of this genus was rejected by Botero-Trujillo & Noriega (2011) who synonymized it with Ananteris. The conclusions of Botero-Trujillo & Noriega (2011) were, however biased by a number of imprecisions, already exposed (Lourenço 2011), and reaffirmed once again here: 1) most, if not all, data proposed by these authors were simply collected in the literature (mainly from my own publications); 2) the holotype of Microananteris minor, type specimen of the genus was not examined, as well as the material of the several groups they used to support their argumentation; 3) the key characters used to separate Microananteris and Ananteris, based on the shape of peg sensillae and the presence of a setae-like structure of the tegument (see Lourenço 2003 for details and illustrations) were equally rejected by Botero-Trujillo & Noriega (2011). Nevertheless, as I explained in a previous paper (Lourenço 2011), the scanning electronic microscope (SEM) photos presented by Botero-Trujillo & Noriega (2011) clearly suggest that the material used by these authors was very poorly preserved for the production of SEM photos, explaining the "absence" of some structures, such as the seta-like tegument, which was most certainly lost during the preparation of the material for SEM observation.
Subsequently Recently, new material belonging to the genus Microanan teris from French Guiana was studied and this leads to the description of two new species. The addition of these two new species brings further evidence about the validity of this genus which remains endemic to French Guiana until now (Fig. 1).
A key for identification of Microananteris species is proposed.

MATERIAL AND METHODS
Illustrations and measurements were produced using a Wild M5 stereo-microscope with a drawing tube (camera lucida) and an ocular micrometer. Measurements (in mm) follow Stahnke (1970), trichobothrial notations Vachon (1974), morphological terminology mostly Hjelle (1990), and cheli-cerae dentition Vachon (1963). The type material of the new species described here will be deposited in the Muséum national d'Histoire naturelle (MNHN), Paris. Revised diagnosis. -Small scorpions, when compared with the average size of a large number of species of micro-buthid genera; the total length of the three known species ranges from 13.07 to 14.00 mm in total length (see Table 1). Microananteris is characterized among several micro-buthoids and in particular in relation to the genus Ananteris Thorell, 1891 by the presence of very small pectines, with the most distal tooth rounded and the most proximal absent (Fig. 2); the total number of teeth ranges from 10 to 11 in both sexes; the structure of the peg sensillae of the pectines is distinct, showing a rounded structure instead of the spatula-like structure observed in Ananteris species. Spiracles have a semi-oval shape. The sternum is subpentagonal. The Telson is more to globular in shape and the aculeus is short. Trichobothriotaxy: orthobothriotaxy type A-β (Vachon 1974(Vachon , 1975. Tibial spurs developed on leg IV but reduced on leg III. The species of the genus Microananteris are exclusively known from humid forests of French Guiana and correspond to possible endemic elements of the soil fauna.  Table 1). Anterior margin of carapace with a weak median concavity. Very small pectines with 10-10 teeth. Spiracles with a semi-oval shape. Telson without granulations, almost smooth. Dorsal carinae of metasomal segments II-IV with weakly marked spinoid granules. Trichobothria: Eb 2,3 of chela hand in a distal position; dt and db of fixed finger basal in relation to et; d 5 and e 1 of femur aligned at the same level.  etymology. -The specific name refers to the strong serrulas present on metasomal segments II to IV.

Microananteris minor
diagnosis. -Total length, including telson 14.00 mm (see Table 1). Anterior margin of carapace straight. Small pectines with 10-11 teeth. Spiracles with a semi-oval shape. Telson with a moderate granulations laterally. Dorsal carinae of metasomal segments II-IV with strongly marked spinoid granules forming serrulas. Trichobothria: Eb 2,3 of chela hand in a more proximal position; dt and db of fixed finger distal in relation to et and est; i trichobothrium of patella very close to d 5 ; femur trichobotrium d 5 distal in relation to e 1 .
descRiption Based on female holotype Coloration Basically brownish-yellow, symmetrically marbled with dark brown, producing an overall spotted appearance. Prosoma: carapace yellow, largely covered with brown spots; eyes surrounded by black pigment. Mesosoma: pale brown-yellow with confluent yellow stripes. Metasomal segments I to V yellowish with several pale brown spots; segment V with better marked spots ventrally. Telson: vesicle yellow with brownish spots laterally and ventrally; aculeus yellow at base and reddish at tip. Venter globally pale yellow. Chelicerae yellow with variegated spots over most of surface; better marked anteriorly; fingers yellow with reddish teeth. Pedipalps yellowish densely marked with pale brownish spots which are better marked on femur and patella; chela slightly paler than patella; fingers brownish with rows of granules slightly reddish. Legs yellow densely marked with brownish spots.

Morphology
Carapace moderately granular; anterior margin straight. Anterior median superciliary and posterior median carinae weak. All furrows moderate to weak. Median ocular tubercle distinctly anterior to the centre of carapace; median eyes separated by c. 0.60 of one ocular diameter.  Vachon 1974Vachon , 1975. Legs: tarsus with very numerous fine diagnosis. -Total length, including telson 13.90 mm (see Table 1). Anterior margin of carapace straight. Large pectines with 10-10 teeth. Spiracles with a semi-oval shape. Telson more elongate without granulations, almost smooth. Dorsal carinae of metasomal segments II-IV with weakly to moderately marked spinoid granules. Trichobothria: Eb 2,3 of chela hand in a proximal position; dt of fixed finger distal in relation to et and est; d 5 trichobothrium of patella very close to the internal face; femur trichobotrium d 5 slightly distal in relation to e 1 . descRiption Based on male holotype Coloration Basically brownish-yellow, symmetrically marbled with dark brown, producing an overall spotted appearance. Prosoma: carapace yellowish, almost totally covered with brown spots; eyes surrounded by black pigment. Mesosoma: brown-yellow with confluent yellow stripes. Metasomal segments I to V yellow with several brownish spots; segment V slightly more spotted. Telson: vesicle yellow without spots laterally or ventrally; aculeus yellowish. Venter pale yellow; coxapophysis slightly marbled with brownish. Chelicerae yellow with variegated spots over the entire surface; more marked anteriorly; fingers yellow slightly spotted; teeth reddish-yellow. Pedipalps: brownish with some paler zones; brownish spots better marked on the femur and patella; chela paler than patella; fingers brownish with the rows of granules slightly reddish. Legs yellow, densely marked with brownish spots.

Morphology
Carapace moderately granular; anterior margin straight. Anterior median superciliary and posterior median carinae weak. All furrows moderate to weak. Median ocular tubercle distinctly anterior to the centre of carapace; median eyes separated by approximately 0.60 of one ocular diameter.  almost smooth. Movable fingers with 6-6 almost linear rows of granules; two accessory granules present at the base of each row; extremity of movable fingers with three accessory granules.

DISCUSSION
As previously discussed (Lourenço 2005), juvenile forms of Ananterinae proved to be rare when collected by standard methods. Most specimens of these cryptozoic but epygean species were obtained almost exclusively by extractions methods. This observation leads to consider the possible evolution of micro-scorpions from endogeous to epygean environments. Scorpions became adapted to terrestrial environments between the Carboniferous and Triassic periods (Jeram 2001;Lourenço & Gall 2004). It can be therefore suggested that transitional forms probably existed then, although these are difficult to identify (Jeram 2001). The early terrestrial forms would have been unable to survive in dry or extreme environments such as savannas or deserts which are today colonized by numerous species. According to their degree of adaptation to life on land, different types of substract were probably used in different stages of the evolution and adaptation of early scorpions. The evaporating power of the air is the most important physical factor of the environment affecting the distribution of cryptozoic animals. This is because small creatures have a very large surface in proportion to their mass; consequently, the conservation of water is the prime physiological problem of their existence (Cloudsley- Thompson 1967Thompson , 1988Little 1983). The majority of cryptozoic animals are restricted to moist conditions, although these must be sufficiently drained to avoid waterlogging. It is probable that the evolutionary transition of many invertebrates from aquatic to terrestrial life may have taken place via the soil where aerial respiration is not associated with desiccation (Cloudsley- Thompson 1967Thompson , 1988; Little 1983). The present eco-physiological characteristics of species belonging to the genus Ananteris and Microananteris suggest that this lineage was originally composed of soil dwellers. During evolutionary time adult forms learned to explore the epygean environment, but juveniles, and also numerous species, remained endogean and kept the plesiomorphic character. This particular situation is more frequently observed in insects but rare within scorpions in general (Wallwork 1970;Gobat et al. 2003).