A new spider species, Selenogyrus foordi sp. nov. (♂♀), is described from Mount Nimba, Guinea. Consequently, we provide the first in vivo photographs of a selenogyrine in the scientific literature and the first record of Selenogyrinae Smith, 1990 from Guinea. We also record S. aureus Pocock, 1897, described from Sierra Leone, from Massif du Ziama Biosphere Reserve, Guinea, representing the second known species for this country.

distribution, morphology, spider, tarantula, taxonomy

Pocock (1897) described the genus Selenogyrus Pocock, 1897 to house two new species from Sierra Leone: S. caeruleus Pocock, 1897 (the type species) based on the female and S. aureus Pocock, 1897 based on the male. In the same work, he also transferred Hapalopus africanus Simon, 1887, which was described from the Ivory Coast based on the female by Simon (1887), newly combining this taxon as Selenogyrus africanus. For the next nine decades, the genus received no revisionary attention. However, it was overlooked by Pocock (1897) that Simon (1892: 139, 141) had indirectly transferred H. africanus to the genus Cyclosternum Ausserer, 1871, another genus to which it clearly did not belong (both Cyclosternum and Hapalopus Ausserer, 1875 are New World genera with urticating setae, and Hapalopus also possesses an abdomen pattern), which is where it was technically combined. Hirst (1908) illustrated the prolateral face of the chelicera of S. aureus as part of a broader work, but only for comparison purposes.

Smith (1986, 1987) presented drawings of the palpal bulb (in retrolateral view) and the tibial apophysis (in ventral view) of S. aureus, also providing a minimalistic redescription. He also gave a short redescription of S. caeruleus (as S. “coeruleus”, a lapsus calami and incorrect subsequent spelling) but without illustrations. Selenogyrus africanus and S. brunneus Strand, 1907 (an enigmatic species described from ‘Western Africa’ based on a supposed female, later relegated as a nomen dubium by Nentwig et al. 2020) are simply listed, with neither descriptions nor illustrations.

Smith (1990) later provided more expansive redescriptions of S. aureus and S. caeruleus, also describing a new species based on a single female from Sierra Leone – Selenogyrus austinius Smith, 1990 (note: the World Spider Catalog (2024) considers this epithet a lapsus calami and corrected the spelling to austini, which we also follow here). He also established a new subfamily, Selenogyrinae Smith, 1990, to house Selenogyrus, predominately based on the remarkable intercheliceral stridulatory apparatus. All three species were illustrated and redescribed in relative detail. Conversely, S. africanus was not redescribed as Smith (1990) was unable to access the type specimen, and S. brunneus is provided with a brief textual redescription but lacking illustrations. Nonetheless, Smith (1990) made the most significant advance in the taxonomy of the genus since its description by Pocock (1897). As mentioned above, the only other taxonomic act was that by Nentwig et al. (2020) who treated S. brunneus as a nomen dubium, primarily as the type material was destroyed during the Second World War.

Hitherto, the only taxonomic illustrations in the literature after Smith (1990) was by Schmidt (1993, 2003) who reproduced drawings from the earlier literature of S. aureus and S. austini respectively, making no novel taxonomic contributions to the genus Selenogyrus nor textual redescriptions. The World Spider Catalog (2024) currently recognises four species, three from Sierra Leone (S. aureus, S. caeruleus and S. austini) and one from the Ivory Coast (S. africanus), all known from a single sex. The species known from females are in urgent need of review and more material from Sierra Leone is needed to confirm whether they are valid. This work is outside the scope of the present one and is being undertaken by a colleague (R. Gallon pers. comm.).

In this work, we describe a new species of Selenogyrus based on type material of both sexes from Mount Nimba, Guinea, which is a notable African biodiversity hotspot where a number of new spiders have been described during the present century (e.g. Rollard and Wesołowska 2002; Zonstein 2018). Simultaneously, we provide the first record of the subfamily Selenogyrinae from Guinea and provide, to our knowledge, the first published photographs of a selenogyriine in vivo. Selenogyrus aureus is also newly recorded for Guinea.

Specimens were examined under binocular microscopes. Photographs of the palpal bulb, tibial apophysis, spermathecae, and habitus were made by DS using a Leica DMC500 digital camera mounted on a Leica MZ16A and stacked using the Leica Application Suite (LAS) v. 4.13. Abbreviations, Repositories: NHMUK = Natural History Museum, London, United Kingdom; RMCA = Royal Museum for Central Africa, Tervuren, Belgium. Structures: A = apical keel (of embolus); ALE = anterior lateral eyes, AME = anterior median eyes, PLE = posterior lateral eyes, PME = posterior median eyes; PB = prolateral branch (of tibial apophysis), PS = prolateral superior keel (of embolus); RB = retrolateral branch (of tibial apophysis), RS = retrolateral superior keel (of embolus). Other: coll. = collector; colln. = collection; det. = determined by. Leg spine terminology follows Petrunkevitch (1925) with modifications: = dorsal, v = ventral, r = retrolateral, p = prolateral. Leg formulae start with the longest leg to the shortest in order of decreasing size, e.g. 4,1,2,3. All measurements are in mm. Maps were made using SimpleMappr (Shorthouse 2010). Type material of the new species is deposited in RMCA. Micro-computed tomography analyses were performed by AH, the structures were dehydrated in graded ethanol (70–95%) and stained with a 1% Lugol’s iodine solution for 24 hours. After washing in pure acetone, the samples were air-dried for 24 hours, and then gently fixed with a piece of tape on a carbon stick. The pieces were scanned with an XREUniTOM (Tescan XRE, Ghent, Belgium) piloted with Acquila software, at 70 keV and 2 W (additional settings: exposure time: 500–700 ms, voxel size: 0.97–1.52 μm, total of 2000 projections). The obtained model was first processed with the Acquila reconstruction software windows version 1.1, followed by segmentation and mesh generation in the 3D analysis Windows-based software Dragonfly 2019 (Object Research Systems (ORS), Canada, https://www.theobjects.com/dragonfly/index.html). The model was further processed in GOM Inspect (https://www.gom.com). In accordance with the International Code of Zoological Nomenclature, this article was registered in ZooBank prior to publication: https://zoobank.org/6D1528B6-39B6-46C1-B46E-3E1C2EF65C42.

Theraphosidae Thorell, 1869

Selenogyrinae Smith, 1990

Selenogyrus Pocock, 1897

 Selenogyrus foordi sp. nov.

https://zoobank.org/F659090C-B69A-4DB2-8D0F-810C4413E5C6

Material examined

Holotype : Guinea • 1♂; Keoulanta, Mount Nimba, Guinea, (7°42'23"N, 8°20'48"W; 515 m a.s.l.; 20/11/2017; C. Allard, P. Bumou, A. Henrard, D. Van den Spiegel, A. Samoura, and M. Bamba leg.; NIMBA-2017-088; BE_RMCA_ARA.Ara.246088.

Paratype : Guinea • 1♀; Seringbara, Mount Nimba, Guinea, 7°40'N, 8°26'W; 599 m a.s.l.; gallery forest; 09/10/2008; D. Van den Spiegel leg.; BE_RMCA_ARA.Ara.222490.

Diagnosis

Males of Selenogyrus foordi sp. nov. can be distinguished from S. aureus by the thinner apical taper of the embolus (embolus wider at apex in S. aureus) and the presence of darkened femora and white markings on the distal third tibiae in vivo (femora with golden tinge and lacking white markings on the distal third of the tibiae in S. aureus). Females of S. foordi sp. nov. can be distinguished from S. africanus, S. austini, and S. caeruleus by the medially flared receptacles of the spermathecae (not medially flared in S. africanus, S. austini, and S. caeruleus).

Etymology

The specific epithet is an eponym honouring our colleague the late Stefan Foord (1971–2023), in recognition of his significant contributions to African arachnology, and in remembrance of his kind and collaborative spirit.

Description of holotype male

(BE_RMCA_Ara.246088). Total length including chelicerae: 26.7. Carapace: (damaged) length 12.0, width 10.5. Caput: slightly raised. Ocular tubercle: (damaged during capture, not measurable). Eyes (interpreted in life): AME > ALE, ALE > PLE, PLE > PME, anterior eye row procurved, posterior row slightly recurved. Clypeus: narrow; clypeal fringe: long. Fovea: deep, procurved. Chelicera: length 4.3, width 1.8. Abdomen: length 10.4, width 6.4. Maxilla with 100–150 cuspules covering approximately 32% of the proximal edge. Labium: length 1.2, width 1.5, with 200–220 cuspules most separated by 0.5–1.0 × the width of a single cuspule. Labio-sternal mounds: separate, raised. Sternum: length 4.9, width 3.6, with three pairs of sigilla. Tarsi I–II and IV fully scopulate, tarsus III missing (but confirmed undivided in paratypes examined). Metatarsal scopulae: I 85%; II 78%; III 43%; IV 17%. Lengths of legs and palpal segments: see Table 1, legs 4,1,2,3. Spination: femur I d 0–0–1, II d 0–0–1, palp d 0–0–1, patella III p 0–0–1, tibia II d 0–2–1, v 2–1–3, III d 2–2–2, v 3–1–3, IV d 1–1–2, v 2–1–3, palp p 0–1–2, metatarsus I v 0–0–1 (apical), II v 2–0–3 (apical), III d 2–2–3, v 3–2–3 (apical), IV d 4–6–3, v 4–6–6 (3 apical). Tibia I with paired tibial apophysis, RB longer than PB, PB with 2 prolateral megaspines situated medially, almost as long as branch; RB with one prolatero-apical megaspine, much shorter than branch (Figs 4A–F, 5A–F). Femur III: slightly incrassate. Palpal tibia: unmodified. Palpal cymbium: unmodified. Metatarsus I: straight, unmodified. Posterior lateral spinnerets with three segments, basal 1.1, median 0.5, digitiform apical (missing). Posterior median spinnerets with one segment. Palpal bulb with TH weakly developed; embolus filiform, tapering strongly in apical third; PS, RS, and A weakly developed, PS and RS apically fused (Figs 2A–I, 3A–D). Stridulation organ: prolateral face of chelicera furnished with clavate stridulatory lyra. Colour in alcohol: brown (Figs 1A–B).

Table 1.

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Selenogyrus foordi sp. nov. holotype male (BE_RMCA_ARA.Ara.246088), podomere lengths, * = missing segment, ≥ = total length calculated based solely on measurements of known segments in each case and thus will differ from true total length.

	I	II	III	IV	Palp
Femur	12.6	11.4	10.0	13.6	7.2
Patella	6.0	5.7	4.6	5.3	3.5
Tibia	10.4	9.5	7.2	11.0	6.9
Metatarsus	11.1	10.1	11.6	16.5	–
Tarsus	7.4	5.5	*	7.0	2.3
Total	47.5	42.2	≥33.4	53.4	19.9

Figure 1. 

Selenogyrus foordi sp. nov. holotype male (BE_RMCA_ARA.Ara.246088) A close-up of carapace (damaged), dorsal view B close-up of maxilla, labium, and sternum, ventral view. Scale bars: 5 mm.

Figure 2. 

Selenogyrus foordi sp. nov. holotype male (BE_RMCA_ARA.Ara.246088), palpal bulb (left-hand side) A prolateral view B retrolateral view C dorsal view D ventral view E close-up of embolus, prolatero-dorsal view F close-up of embolus, retrolateral view G close-up of embolus, dorsal view H close-up of embolus, ventral view I close-up of embolus, ventro-retrolateral view. Scale bars: 1 mm (A–D); 0.1 mm (E–I).

Figure 3. 

Selenogyrus foordi sp. nov. holotype male (BE_RMCA_ARA.Ara.246088), micro-computed tomography of palpal bulb (left-hand side) A prolateral view B retrolateral view C dorsal view D ventral view.

Figure 4. 

Selenogyrus foordi sp. nov. holotype male (BE_RMCA_ARA.Ara.246088), tibial apophysis (left-hand side) A prolateral view B ventral view C retrolateral view D close-up, prolateral view E close-up, ventral view F close-up, retrolateral view. Scale bars: 2 mm (A–C); 0.5 mm (D–F).

Figure 5. 

Selenogyrus foordi sp. nov. holotype male (BE_RMCA_ARA.Ara.246088), micro-computed tomography of tibial apophysis (left-hand side) A prolateral view B prolatero-ventral view C ventral view D ventro-apical view E retrolateral view F dorso-retrolateral view.

Description of paratype female

(BE_RMCA_ARA.Ara.222490). Total length including chelicerae: 52.3. Carapace: length 20.0, width 18.0. Caput: raised. Ocular tubercle: slightly raised, length 3.3, width 1.5. Eyes: ALE > AME, AME > PLE, PLE > PME, anterior row procurved, posterior row recurved. Clypeus: narrow; clypeal fringe: short. Fovea: deep, procurved. Chelicera: length 12.3, width 8.3. Abdomen: length 24.0, width 15.5. Maxilla with 160–180 cuspules, covering approximately 40% of proximal edge. Labium: length 2.7, width 3.4, with 130–160 labial cuspules most separated by 0.5–1.0 × the width of a single cuspule. Labio-sternal mounds: separate, raised. Sternum: length 8.7, width 7.8, with three pairs of sigilla. Tarsi I–IV fully scopulate. Metatarsal scopulae: I 83%; II 65%; III 49%; IV 23%. Lengths of leg and palpal segments: see Table 2, legs 4,1,2,3. Spination: femur palp d 0–0–1, tibia I v 0–0–3, II v 0–0–3, III v 2–1–2, p 0–1–0, r 0–1–0, IV v 1–1–3, p 0–1–0, r 0–1–1, palp p 0–2–2, r 0–0–2, metatarsus I r 0–0–3, II r 0–0–3, III d 0–0–2, v 2–2–4 (3 apical), p 1–1–2, r 1–1–0, IV v 3–4–5 (3 apical), r 1–1–0. Posterior lateral spinnerets with three segments: basal 2.2, medial 2.0, digitiform apical 3.3. Posterior median spinnerets with one segment. Spermathecae with two distinct and separate receptacles, basally wider than apex, medially with prolateral and retrolateral flaring, tapering gently thereafter to apex, each receptacle with a single indistinct lobe without neck constriction (Fig. 2D). Stridulation organ: prolateral face of chelicera furnished with clavate stridulatory lyra (Fig. 2C). Colour in alcohol: brown (Figs 2A–B).

Table 2.

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Selenogyrus foordi sp. nov. paratype female (BE_RMCA_ARA.Ara.222490), podomere lengths.

	I	II	III	IV	Palp
Femur	16.4	14.4	12.5	16.8	5.8
Patella	9.4	6.5	7.1	8.1	3.0
Tibia	12.5	10.2	8.2	12.1	3.8
Metatarsus	11.2	10.1	11.1	17.1	–
Tarsus	7.3	7.1	5.7	7.7	4.0
Total	56.8	48.3	44.6	61.8	16.6

Colour

in vivo. Male with carapace with turquoise pubescence, with alternating radial bands of fawn and dark green, lateral margins with bands of sepia-coloured bristles, anterior margin fawn. Chelicerae with tawny-brown bristles, endites with long red-brown bristles apically. Palp dark brown, apically with a white blotch. Legs: femora dark brown, with long brown bristles ventrally; patellae dark brown with some lighter bristles; tibiae brown in proximal half and white in distal half; metatarsi light brown with distal part paler; tarsi light brown; all legs with numerous long light bristles, more densely distributed on legs 3 and 4. Abdomen dark brown, with a slightly coppery sheen and light, long, brown bristles; spinnerets brown (Figs 6A–C). Female overall black, with orange-red hairs densely distributed on legs (Fig. 7E).

Figure 6. 

Selenogyrus foordi sp. nov. holotype male (BE_RMCA_ARA.Ara.246088), habitus in situ at type locality A general view B same, on different background C frontal view, specimen in defensive posture.

Figure 7. 

Selenogyrus foordi sp. nov. paratype female (BE_RMCA_ARA.Ara.222490) A habitus, dorsal view B habitus, ventral view C chelicera, prolateral view (inset: close-up of stridulatory lyra) D spermathecae, dorsal view E habitus in vivo. Scale bars: 10 mm (A–B); 0.5 mm (D); 0.1 mm (C).

Distribution

Known only from Mount Nimba, Guinea.

New distribution record

 Selenogyrus aureus Pocock, 1897

Selenogyrus aureus Pocock, 1897: 768, pl. 41, fig. 2.

Selenogyrus aureus: Hirst, 1908: 402, fig. 1.

Selenogyrus aureus: Smith, 1987: 98, fig. 100h.

Selenogyrus aureus: Smith, 1990: 138, figs 892–911.

Selenogyrus aureus: Schmidt, 1993: 58, figs 35.

Selenogyrus aureus: Schmidt, 2003: 116, fig. 63.

Material examined

Holotype : Sierra Leone • 1♂; Sierre Leone [sic!]; no collector or date given; NHMUK 1865.83.

Non-type : Guinea • 1♂; Massif du Ziama Biosphere Reserve, Guinea, 8°24'N, 9°17'W; pitfall traps in rainforest; 10/07/1998; leg. D. Flomo; BE_RMCA_ARA.Ara.216682 • 1♂; same data except 23/07/1998; BE_RMCA_ARA.Ara.216680 • 1♂; same data except 13/04/1998; BE_RMCA_ARA.Ara.216681 • 1♂; same data except no date; BE_RMCA_ARA.Ara.216683.

Diagnosis

See diagnosis for S. foordi sp. nov.

Distribution

Guinea (new record) and Sierra Leone (World Spider Catalog 2024).

Remarks

We provide photomicrographs of the palpal bulb of the holotype male (Figs 8A–D) to assist in identification of this species, but do not give a full description of the specimen since this will be forthcoming in a separate work by another colleague (R. Gallon pers. comm.).

Figure 8. 

Selenogyrus aureus Pocock, 1897 holotype male (NHMUK 1865.83), palpal bulb (left-hand side) A prolateral view B retrolateral view C dorsal view D ventral view. Scale bars: 1 mm.

First and foremost, we warmly thank Galina Azarkina (Institute of Systematics and Ecology of Animals, Novosibirsk) and John Midgeley (KwaZulu-Natal Museum, Durban) for invitation to submit this work to the special issue commemorating Stefan Foord. We also thank Richard Gallon (British Arachnological Society) for his helpful comments and for allowing us to publish the new species description ahead of his revision of the African theraphosid subfamilies. Pedro Peñaherrera-R. (Universidad San Francisco de Quito, Ecuador) is thanked for discussion on embolar keel homology. We also thank Sergei Zonstein (Steinhart Museum of Natural History) and Ansie Dippenaar-Schoeman (South African National Survey of Arachnida) for their comments which improved the final manuscript.