Ammonius Thorell, 1899

Gonzalez-Filho, Hector M. O., Guadanucci, José Paulo L. & Brescovit, Antonio D., 2023, On the genus Ammonius Thorell, 1899 (Mygalomorphae, Barychelidae): description of the female of A. pupulus, a new species and new distribution records, European Journal of Taxonomy 861 (1), pp. 113-131 : 115-116

Genus Ammonius Thorell, 1899

Ammonius Thorell, 1899: 10 .

Ammonius – Simon 1903: 915. — Benoit 1965: 7. — Raven 1985: 113.

Type species

Ammonius pupulus Thorell, 1899 , by monotypy.

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 ).

Description

Very small spiders, total length between 3.9–7.3. General coloration yellowish light brown ( Figs 1A–B , 5A–B , 8A–B ). Abdomen dorsally pale without pattern and spinnerets pale with some brown light setae on dorsal side ( Figs 1F , 8A ). Carapace ovate ( Figs 1A , 5A , 8A , 9A ). Thoracic fovea small and straight ( Figs 1A , 5A , 8A ). Clypeus narrow ( Figs 1D , 4B , 5D , 9B ). Eye tubercle black and flat ( Figs 1D , 5D ). Eye group in rectangular shape, anterior and posterior eye rows straight ( Figs 1D , 4B , 5D , 9D ). Ammonius pupulus with eight eyes ( Figs 1D–E , 4B , 5D ); A. benoiti sp. nov. with six eyes, AME absent ( Fig. 9A– B ). Labium rectangular, 2–6 cuspules rounded. Maxillae rectangular with 3–20 cuspules on inner corner, maxillary hell reduced. Anterior lobe short, not projected ( Figs 1C , 4C , 5C ). Maxillary lyra absent. Rastellum absent, distal edge of maxilla with thick setae ( Figs 1C , 5C ). Intercheliceral tumescence in males absent. Labiosternal groove shallow, flat, with pair of sigilla ( Fig. 4C ). Book lungs semi-circular, opening elliptical, and book lung combs absent. Plumose clavate trichobothria in two rows on distal half on all tarsi ( Fig. 4D ). Claws: ITC absent. STC with parallel row of teeth present on lateral edge on males and absent in females ( Figs 4E , 6A , 7A ). Frictional setae present in all tarsi, very evident, longer and inserted below the claw tuft plate ( Figs 4E–F , 6A–B , 7A ). Scopulae: on metatarsi I–II scopulate and absent on metatarsi III–IV; on tarsi I fully scopulate and tarsi II–IV slightly scopulate. Four spinnerets, PMS very small, PLS long with apical segment digitiform ( Fig. 1F ), with several spigots on apical half ( Fig. 4A ). Male palpal tibia with a ventral concavity in A. pupulus ( Figs 2E , 3A–B ), absent in A. benoiti . Tibial thorns on the retrolateral side of the palp in A. benoiti ( Figs 8D–E , 9D ). Tibial spur absent. Megaspine on the tibia I in A. benoiti ( Figs 8J , 9E ). Male palpal bulb with globose subtegulum, with thin and sinuous embolus in A. pupulus ( Fig. 2A–G ), and slightly curved embolus in A. benoiti ( Fig. 8F–I ). Spermathecae with two straight receptacles, external receptacle with globose lobe, emerging from the internal receptacle ( Fig. 5E ).

Included species

Ammonius pupulus Thorell, 1899 ; A. benoiti sp. nov.

Distribution

Cameroon and Ivory Coast ( Fig. 10 ).

Figures

Fig. 1. Ammonius pupulus Thorell, 1899, holotype, ♂ (NHRS-GULI37848). A. Habitus dorsal. B. Habitus ventral. C. Maxillae and labium, ventral view. D–E. Eye group. D. Dorsal view. E. Detail of the eye arrangement. F. Abdomen, lateral view. Scale bars: A–B, F = 1 mm; C–E = 0.5 mm.

Fig. 4. SEM micrographs of Ammonius pupulus Thorell, 1899, ♂ (RMCA 227221). A. Apical segment of PLS. B. Eye group, lateral view. C. Maxillae and labium, ventral view. D. Clavate trichobothria. E. Apical of the tarsus I, lateral view. F. Detail of frictional setae, lateral view. Abbreviations: Ch = chemosensory setae; CT = claw tufts; FS = frictional setae; STC = superior tarsal claws. Scale bars: A, F = 50 µm; B = 300 µm; C = 500 µm; D = 5 µm; E = 100 µm.

Fig. 5. Ammonius pupulus Thorell, 1899, ♀ (RMCA 227221). A. Habitus dorsal. B. Habitus ventral. C. Maxillae and labium, ventral view. D. Eye group, dorsal view. E. Spermathecae. F. Sternum, ventral view. Scale bars: A–B = 1 mm; C–D, F = 0.5 mm; E = 0,02 mm.

Fig. 9. SEM micrographs of Ammonius benoiti sp. nov. (RMCA 202354). A. Carapace, dorsal view. B. Eye tubercle, dorsal view. C. Tibia I, prolateral view. D. Detail of tibial thorns, retrolateral view. Abbreviations: ALE = anterior lateral eyes; PLE = posterior lateral eyes; PME = posterior median eyes. Scale bars: A = 0.5 mm; B–C = 0.3 mm; D = 0.1 mm.

Fig. 2. Male palp of Ammonius pupulus Thorell, 1899. A–D. Holotype, ♂ (NHRS-GULI37848). A. Dorsal view. B. Ventral view. C. Prolateral view. D. Retrolateral view. E–F. SEM micrographs of the male palp of Ammonius pupulus (RMCA 227221). E. Prolateral view. F. Retrolateral view. G. Drawing from Benoit (1965: fig. 1), ventral view. Abbreviation: Tc = Tibial concavity. Scale bars: A–D = 1 mm; E–F = 0.5 mm.

Fig. 3. SEM micrographs of the male palp of Ammonius pupulus Thorell, 1899 (RMCA 227221). A–B. Tibial concavity. A. Prolateral view. B. Retrolateral view. C–D. Cymbium. C. Prolateral view. D. Retrolateral view. Abbreviations: Em = embolus; PL = prolateral lobe; So = slit organ; Tc = tibial concavity. Scale bars: A = 400 µm; B = 200 µm; C–D = 400 µm.

Fig. 8. Ammonius benoiti sp. nov. A–E. Holotype, ♂ (RMCA 202482). A. Habitus dorsal. B. Habitus ventral. C–E. Male palp. C. Prolateral view. D. Ventral view. E. Retrolateral view. F–J. Paratype, ♂ (RMCA 202354), male palpal bulb. F. Ventral view. G. Dorsal view. H. Prolateral view. I. Retrolateral view. J. Tibia I, prolateral view. Abbreviations: Ms = Megaspine; Tt = Tibial thorns. Scale bars: A–E, J = 0.5 mm; F–I = 0.2 mm.

Fig. 6. SEM micrographs of Ammonius pupulus Thorell, 1899, ♂ (RMCA 169417), tarsus I. A. Lateral view. B. Detail of frictional setae, lateral view. C–D. Detail of the chemosensory setae. Abbreviations: Ch = chemosensory setae; ChM = chemosensory setae male; CT = claw tufts; FS = frictional setae; STC = superior tarsal claws. Scale bars: A = 100 µm; B–C = 50 µm; D = 30 µm.

Fig. 7. SEM micrographs of Ammonius pupulus Thorell, 1899, ♀ (RMCA 169416), tarsus IV. A. Lateral view. B. Detail of macrosetae, lateral view.C. Chemosensory setae.D. Apical detail of the chemosensory setae. E. Scale setae. F. Chemosensory setae. Abbreviations: Ch = chemosensory setae; CT = claw tufts; FS = frictional setae; STC = superior tarsal claws. Scale bars: A = 100 µm; B–C = 50 µm; D = 20 µm; E = 50 µm; F = 30 µm.

Fig. 10. Distribution map of the presently known species of the genus Ammonius Thorell, 1899.