On the genus Ammonius Thorell, 1899 (Mygalomorphae, Barychelidae): description of the female of A. pupulus , a new species and new distribution records

. Among the 40 genera of Barychelidae, only nine genera are described from the African continent. Thorell (1899) described Ammonius Thorell, 1899 based on a male from Cameroon. In 1965 Benoit added more information from the holotype, with detailed illustrations of the male palp bulb and the eye group. Since then, few taxonomic revisions or new species of Barychelidae have been proposed from the African continent. Ammonius can be distinguished by the strongly pronounced retrolateral lobe of the male cymbium and the aspect of the bilobed spermathecae of the female. We redescribe the holotype male of A. pupulus Thorell, 1899 and describe the female for the first time. Additionally, a new species is described: Ammonius benoiti sp. nov., from Ivory Coast. The morphology of the tarsal setae is presented through SEM photographs. New distribution records of the genus are provided.

Until the mid-1960s, the African fauna of Barychelidae was poorly known until Pierre L.G. Benoit began his studies on some Mygalomorphae Pocock, 1892 from Central Africa while working at the Royal Museum for Central Africa (RMCA).During the years 1964-1966, Benoit published several works reviewing and proposing new species of African barychelids.Since then, no new species have been described and much of the information available is present only in the original descriptions.
The genus Ammonius Thorell, 1899 was proposed based on a single male specimen from Cameroon without precise locality.Later in 1965, Benoit redescribed the holotype in more detail, adding informative new illustrations of the male palp bulb and the eye group.Raven (1985), in his comprehensive revision of Mygalomorphae, reported the barychelid intrarelationships, which presented that Ammonius is related to Eubrachycercus Pocock, 1897 and Thalerommata Ausserer, 1875, forming a monophyletic group with other subfamilies, however no subfamily has been assigned to them.
In the present paper, we present a redescription and provide new multifocal and SEM photos of A. pupulus Thorell, 1899.Also, based on specimens of Barychelidae deposited in the Royal Museum for Central Africa, Tervuren, Belgium, we describe the female of A. pupulus for the first time.Furthermore, we describe a new species from the Ivory Coast, report, characterize and discuss morphological setae present on leg and extend the distribution of the genus to the Ivory Coast.

Repositories
The material examined is deposited in the following institutions (curators in parentheses): NHRS = Swedish Museum of Natural History, Stockholm, Sweden (Anna Gauffin) RMCA = Royal Museum of Central Africa, Tervuren, Belgium (Didier Van den Spiegel)

Measurements
The specimens were examined under a LEICA S8AP0 stereo microscope.All measurements are in millimeters.Total body length includes carapace and abdomen without chelicerae and spinnerets.Length and width of carapace, eye tubercle, labium and sternum are maximum values obtained.The length measurement of leg segments was obtained between joints in dorsal view.Terminology for number and disposition of spines follow Petrunkevitch (1925), with the modifications proposed by Bertani (2001).

Illustrations
Digital multifocal photos were taken with a Leica DFC500 digital camera attached to a Leica MZ16A stereoscopic microscope.Extended focal range images were composed with Leica Application Suite ver.2.5.0.The specimens were prepared for scanning electron microscopy (SEM) following Galleti-Lima & Guadanucci (2019).SEM photos were taken on a FEI Quanta 250 SEM at the Laboratório de Biologia Celular, Instituto Butantan and a Hitachi TM-1000 at the Laboratório de Microscopia Eletrônica of the Institute of Biosciences of São Paulo State University, Rio Claro, São Paulo.
The spermathecae were dissected and submitted to digestion of the non-chitinous tissue by Ultrazyme ® Enzymatic Cleaner for 24 hrs, where a tablet was diluted in 5 mL of distilled water.The internal structure was illustrated in dorsal view.The male palpal bulb was removed from the cymbium and illustrated.

Geographical data
Geographic coordinates were obtained through information on the original museum labels.Localities from museum samples without coordinates were georeferenced using Google Earth ® .The geographic distribution of the species was created using SimpleMappr (Shorthouse 2010).

Diagnosis
Ammonius can be distinguished from the other barychelids by the apical segment of the PLS digitiform (Fig. 1F); compact eye group rectangular in shape (Figs 1D, 4B, 5D, 9B), eye tubercle flat; A. pupulus with eight eyes (Figs 1D-E, 4B, 5D); absence of AME in A. benoiti sp.nov.(Fig. 9B); male cymbium unequal, with prolateral lobe inconspicuous and retrolateral lobe strongly projected (Figs 2, 3C-D, 8C-E).Males resemble Pisenor notius Simon, 1889(see Benoit 1966: figs 24, 26) by the strongly pronounced retrolateral lobe of the cymbium but differ by the lack of a spur on tibia I, and the modified palpal tibia, with a tibial concavity in the ventro-prolateral side of the palp on A. pupulus (Fig. 3A-B), and by the presence of a tibial thorn on the retrolateral side of the palp on A. benoiti (Figs 8D-E, 9D).Females of the genus can be distinguished from the other genera by the bilobed spermathecae, with the external stalk small and emerging from the basal region of the receptacle (Fig. 5E).
Habitus as in Fig. 1A-B.Color in alcohol: Carapace and legs dorsally yellowish light brown.Eye tubercle black.Abdomen pale with some brown light setae on dorsal side, abdomen pattern absent (Fig. 1F).Spinnerets pale.
Spermathecae: two long receptacles with wide base; each with a globose lobe on the outer side (Fig. 5E).
Habitus as in Fig. 5A-B.Color in alcohol: same as male.

Diagnosis
Ammonius benoiti sp.nov. is differentiated most readily by having six eyes, AME is absent (Fig. 9A-B).Males of A. benoiti can be additionally distinguished from A. pupulus by the thickened embolus with a slight curve at the tip (Fig. 8F-I), the presence of the tibial thorns on the retrolateral side of the palp (Figs 8D-E, 9D), and an apical megaspine on the tibia I (Figs 8J, 9C).Female unknown.
Habitus as in Fig. 8A-B.Color in alcohol: Carapace and legs dorsally yellowish brown.Eye tubercle black.

Female
Unknown.

Discussion
Barychelidae Simon, 1899 is subdivided into two subfamilies: Barychelinae Simon, 1889 and Sasoninae Simon, 1892 (Mori & Bertani 2020).The position of the eyes on the carapace is one of the key traits that distinguishes the two subfamilies: Sasoninae presents an eye group that is wider than long (rectangular) while Barychelinae presents anterior lateral eyes displaced towards the anterior carapace margin (quadrate or trapezoid).
Thorell (1899) commented that Ammonius pupulus is closely related to the genus Leptopelma Ausserer, 1871 due to the close proximity of the AME and PME in a rectangular shape.Benoit (1965) supported the Fig. 10.Distribution map of the presently known species of the genus Ammonius Thorell, 1899.proposed relationship between the two genera and included Ammonius in the subfamily Leptopelmatinae Simon, 1892.It is worth mentioning that Raven (1990) transferred Leptopelma to Nemesia Audouin, 1826 (Nemesiidae), thus the subfamily name no longer applies to Barychelidae.Furthermore, Raven (1985) left some genera, including Ammonius, as incertae sedis in Barychelidae.Although Ammonius possess the rectangular eye group (Figs 1 D-E, 4B, 5D, 9A-B), a character that supports Sasoninae, the genus was not assigned in Sasoninae due to the digitiform apical segment of the PLS (Fig. 1F).Therefore, in addition to the eye group shape and eye arrangement, the apical segment of PLS may generate an ambiguous interpretation in different cladistic analyses, which require further study to evaluate the morphological variety of these structures.Some mygalomorph genera in other families show a loss or reduction of the eyes, like in the genera Troglodiplura Main, 1969 (Anamidae); Troglothele Fage, 1929 (Barychelidae); Masteria L. Koch, 1873, Striamea Raven, 1981, Siremata Passanha & Brescovit, 2018 (Dipluridae); Euagrus Ausserer, 1875 (Euagridae); Tonton Passanha et al., 2019 (Microstigmatidae); Hemirrhagus Simon, 1903 (Theraphosidae); as well as the species Acontius stercoricola (Denis, 1955) (Cyrtaucheniidae); Harmonicon cerberus Pedroso & Baptista, 2014 (Dipluridae); Hexathele carvenicola Forster, 1968 (Hexathelidae), Spelocteniza ashmolei Gertsch, 1982 (Microstigmatidae) and Tmesiphantes hypogeus Bertani, Bichuette & Pedroso, 2013 (Theraphosidae).Ammonius benoiti sp.nov. is notable for having six eyes (Fig. 9B), but in Barychelidae and most spider groups the normal condition is eight eyes.Synothele subquadrata Raven, 1994 andMandjelia galmarra Raven, 1994 have seven eyes, but Raven (1994) considered that condition as aberrant.In general, the reduction or absence of eyes is more common in cave dwelling species or in aphotic habitats (lack of light), such as spiders of the genus Masteria which are found deep into the leaf litter (Pedroso & Baptista 2014;Passanha & Brescovit 2018).However, it cannot be confirmed that A. benoiti is a cave species, since the original label does not give any information about the specific location of collection.
The general aspect of the male palpal bulb in Ammonius is a globose subtegulum, thin and long embolus with a strong constriction at the basal portion (Figs 2, 8C-I).Although in most barychelid genera the embolus is short with a conical aspect (Raven 1994), the species of Ammonius have an embolus thin and sinuous, which could be related to the basal constriction.Moreover, in A. pupulus, the embolus is thinner and has a strong curvature (Fig. 2), different from A. benoiti sp.nov., which has a thicker embolus and a slight curve at the tip (Fig. 8F-I).
In addition to the morphology of the male palpal bulb, two other distinct morphological characters in the male palp can be observed in Ammonius, that are unique to each species and remain a high value in species recognition.First, the presence of a concavity on the ventro-prolateral side of the tibial, in A. pupulus (Figs 2E, 3A-B).The tibial concavity (Tc) is a depression localized in the basal portion of the palp tibia, and seems to be a place where the embolus is accommodated due to its strong curvature (Fig. 3A-B).Also, in A. benoiti sp.nov., on the retrolateral side, a group of strong conical spines is present, named here as Tibial thorns (Tt) (Figs 8D-E, 9D).Compared to the surrounding spines, these spines are shorter and thicker.Moreover, A. benoiti sp.nov., has a curved apical megaspine on the prolateral side of the tibia I (Figs 8J, 9C).This megaspine is in the same position as the spur found in the other barychelids, and potentially could be associated with mating (Raven 1985(Raven , 1994)).However, this hypothesis cannot be confirmed yet because no barychelids mating has been registered (Raven 1994).
In Ammonius, the frictional setae (Fs) are observed in the tarsus tip below the claw tufts (Figs 4E-F, 6A-B, 7A) (Wolff et al. 2013;Guadanucci et al. 2020).These setae are conical with no-spatulate microtrichia, similar to those observed in theraphosid spiders (Guadanucci et al. 2020: fig. 11a-f).These setae are longer than claw tufts and inserted below the claw tufts plate (Figs 4E-F, 6A-B, 7A).Ramírez (2014) named these setae as pseudotenent setae to dionychan spiders, which share some similarities, as well as the morphology and position of insertion.In contrast, Pérez-Miles et al. (2017) treated these as conical setae, however, Guadanucci et al. (2020) highlights some differences such as the condition of the length and width of this band of conical seta.
Other setae are distributed along the tarsi and cymbium, with a greater amount of chemosensory setae on the forelegs.These setae have an open tip, which has a shaft with an internal cuticular tube enclosing the dendrites (see Ramírez 2014: fig.84f).The structure of chemosensory setae present in Ammonius can be divided into three types: basal, median, and apical (Fig. 7F).The basal portion has a grooved surface; the median portion has sharp barbs, and the apical portion has a cord like appearance with a slightly curved tip, which makes contact with the substratum (Fig. 7F).These setae can be found in both sexes.However similar chemosensory setae were only observed in the ventral section of the male, which presents a shorter distal portion (ChM Chemosensory setae male, Fig. 6D).Several scale setae can be observed distributed on the cuticular surface.They are crimped in a small socket, bent at an angle immediately after the insertion, so that they lay parallel to the cuticular surface (Ramírez 2014).We also observed a scale seta with the small barbs interspersed on its stem (Fig. 7E).