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1 August 2015 On the African Crab Spider Genus Geraesta Simon, 1889 (Araneae: Thomisidae)
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Abstract

A new species, Geraesta ansieae sp. n. is described and illustrated. Further, two species are illustrated, diagnosed and transferred from Stephanopis O. Pickard-Cambridge, 1869 to Geraesta Simon, 1889: G. congoensis (Lessert, 1943) comb. n. and G. octolobata (Simon, 1886) comb. n. New localities for G. hirta Simon, 1889 are given and a key to the males of all of the valid species is provided. Stephanopis rhomboidalis Simon, 1886 is considered a nomen dubium.

INTRODUCTION

The genus Geraesta Simon, 1889 is restricted to the Afrotropical Region and currently comprises three poorly studied species (Platnick 2014). The recent examination of African Stephanopinae crab spiders from several museum collections brought to light the presence of a species of the genus that is new to science, as well as new records for two known species. Further, an ongoing study of the genus Stephanopis O. Pickard-Cambridge, 1869 revealed that at least two African species placed in it are misplaced and should be transferred to Geraesta.

MATERIAL AND METHODS

Methodology follows Benjamin (2011). Specimens used for habitus illustrations were placed in 70% ethanol and photographed using a dissecting microscope (Zeiss Discovery V20) with top illumination and a magnification of up to 150×. Digital images were taken with a Zeiss AxioCam HRc camera. Images were edited using the Zeiss ZEN Pro Software Package. Left palps are depicted unless otherwise stated. Setae are usually not depicted in the final palp drawings. All measurements are given in millimetres.

Morphological abbreviations: AER — anterior row of eyes; ALE — anterior lateral eyes; AME — anterior median eyes; C — conductor; CD — copulatory duct; CO — copulatory opening; E — embolus; MA — median apophysis; PER — posterior row of eyes; PLE — posterior lateral eyes; PME — posterior median eyes; RTA — retrolateral tibial apophysis; S — spermatheca; Tr —trichobothrium; VTA — ventral tibial apophysis.

Museum collections (curators are given in parentheses):

CAS

California Academy of Sciences, San Francisco, USA (Charles Griswold)

;

MHNG

Muséum d'Histoire naturelle, Geneva, Switzerland (Peter Schwendinger)

;

MNHN

Muséum national d'Histoire naturelle, Paris, France (Christine Rollard, Elise-Anne Leguin)

;

MRAC

Musée royal de l' Afrique centrale , Tervuren, Belgium (Rudy Jocqué)

;

NCA

National Collection of Arachnida, Agricultural Research Council (ARC) — Plant Protection Research Institute, Pretoria, South Africa (Ansie Dippenaar-Schoeman, Petro Marais).

TAXONOMY

Family Thomisidae Sundevall, 1833
Genus Geraesta Simon, 1889

  • Geraesta Simon, 1889: 224; Benjamin 2011: 15.

  • Type species: Geraesta hirta Simon, 1889, by original designation.

  • Diagnosis: Diagnosed by the presence of two to three trichobothria on the dorsal surface of the male palpal cymbium (Fig. 24; Benjamin 2011: figs 40d, 42b, 43c, 45e) and the presence of at least one serrated apical tibial apophysis (Figs 4, 5, 24–26; Ramírez 2014: fig. 151a). Females can be separated by the presence of opisthosomal lobes (Figs 10, 17, 18). Further, Geraesta can be separated from other African Stephanopinae as follows: from Borboropactus Simon, 1884 by the presence of two to three trichobothria on the cymbium (Fig. 25; Benjamin 2011: figs 40d, 42b, 43c, 45e; Marusik et al. 2013: figs 1–3). Females can be separated from Borboropactus by the presence of epigynal lips and opisthosomal lobes (Benjamin 2011: figs 41e, 42c, 44d, 46d); from Epidius Thorell, 1877 by the absence of an elongated male palpal tibia (tibia is longer than the cymbium in Epidius; Benjamin 2011: fig. 35c) and the absence of 4–6 thick long spines on the distal margin of the male palpal tibia (Benjamin 2011: figs 33b, 35c, 36b). Judging from the illustrations in Ledoux (2004), Prepotelus Simon, 1898 might be a synonym of Geraesta.

  • Description: Geraesta is described in Benjamin (2011).

  • Distribution: This genus is endemic to Africa and is now known from Botswana, Comoros, Democratic Republic of Congo, Ivory Coast, Madagascar, Rwanda, South Africa and Tanzania.

Key to males of Geraesta

  • 1 E short, not winding around the tegulum (Benjamin 2011: figs 44a, 45b) mkwawa Benjamin, 2011

  • - E longer, at least partly winding around the tegulum (Figs 4, 5, 19) 2

  • 2 C present, E winding less than 1.5× around the tegulum (Figs 5, 11, 19) 3

  • - C absent, E winding 1.5× around the tegulum (Figs 14) ansieae sp. n.

  • 3 RTA and VTA present (Benjamin 2011: figs 42a, b) lehtineni Benjamin, 2011

  • - VTA absent 4

  • 4 E winding 0.5× around the tegulum 5

  • - E winding once around the tegulum (Figs 5–8, 12–15) congoensis (Lessert, 1943) comb. n.

  • 5 C spiniform with an acute tip, MA spoon-like with a tapered stalk, opisthosoma with two dorsal protuberances (Figs 9, 10; Benjamin 2011: figs 39a, b, c) hirta Simon, 1889

  • - C sickle-shaped with a short filiform tip, MA sickle-shaped with a stout stalk, opisthosoma with eight whitish dorsal protuberances (Figs 1726) octolobata (Simon, 1886) comb. n.

Geraesta ansieae sp. n.
Figs 14

  • Etymology: Named in honour of Dr Ansie Dippenaar-Schoeman. She has contributed in a big way to our present understanding of the diversity and richness of African crab spiders. Further, she is an inspiration to many African arachnologists.

  • Diagnosis: Males of G. ansieae sp. n. can be distinguished from congeners by the combined presence of the following characters: C absent, MA spoon-shaped with an elongated stalk, filiform E that winds 1.5× around the tegulum, and the single tibial apophysis. Female unknown.

  • Description:

  • Male (holotype).

  • Measurements: total length: 2.7; prosoma length: 1.5, width: 1.5. Leg I: femur 2.9, patella 0.6, tibia 3.0, metatarsus 2.4, tarsus 1.4.

  • Prosoma rounded, yellow-brown, blackish laterally (Fig. 1). Leg formula 2143, ALE > PLE > PME > AME. AER, PER recurved, eyes on light-brown protuberances, but not touching. Legs elongated. Opisthosoma longer than wide, light yellow, with white spots, yellow folium in the centre (Fig. 1). Opisthosoma without tubercles. Palp as in Figs 24, with single tibial apophysis and disc-shaped tegulum; E long, winding 1.5× around tegulum, C absent, MA spoon-shaped with an elongated stalk.

  • Holotype ♂: RWANDA : Eastern Rwanda: Akagera National Park, 01°40′S 30°35′E, 14.xi-10.xii.1985, leg. R. Jocqué, Nsengimana & J.P. Michiels, dried out, right palp missing, some legs missing (MRAC 239298).

  • Remark: Although the type specimen is in a reasonably poor condition, the distinctive morphology of the male palp (long embolus, absence of conductor) leaves no doubt that it is a new taxon that should be described.

  • Distribution: Known only from the type locality.

Figs 1–3.

Geraesta ansieae sp. n. (MRAC 239298): (1) dorsal habitus; (2, 3) left male palp in ventral (2) and retrolateral (3) views. Abbreviations: E — embolus; MA — median apophysis; RTA — retrolateral tibial apophysis. Scale bars = 0.2 mm (2, 3), 1.0 mm (1).

f01_309.jpg

Figs 4–8.

(4) Geraesta ansieae sp. n. (MRAC 239298) and (5–8) G. congoensis (Lessert, 1943) (MRAC 239299): (4, 5) left male palp, ventral view; (6) epigynum, ventral view; (7) vulva, dorsal view; (8) vulva, ventral view. Abbreviations: C — conductor; CD — copulatory duct; CO — copulatory opening; E — embolus; MA — median apophysis; RTA — retrolateral tibial apophysis; S — spermatheca. Scale bars = 0.1 mm (5), 0.2 mm (4, 6–8).

f04_309.jpg

Geraesta congoensis (Lessert, 1943), comb. n.
Figs 5–8, 12–15

  • Stephanopis congoensis Lessert, 1943: 333, figs 35–37.

  • Diagnosis: Males of G. congoensis can be distinguished from congeners by the combined presence of the following characters: needle-shaped C with slight bend just before the tip, spatulate MA with an elongated stalk, and the filiform E that winds once around the tegulum.

  • Description:

  • Male (syntype).

  • Measurements: total length: 7.5; prosoma length: 3.3, width: 2.9. Leg I: femur 3.8, patella 1.2, tibia 3.8, metatarsus 2.9, tarsus 1.2.

  • Leg formula 1243, ALE > PLE > PME > AME. AER, PER recurved, eyes on lightbrown protuberances, but not touching. Palps as in Figs 5, 15: single tibial apophysis, C needle-shaped with slight bend just before the tip, MA spatulate with an elongated stalk. E originates at distal end of the tegulum, winding once around it.

  • Female (syntype).

  • Measurements: total length: 5.4; prosoma length: 2.7, width: 2.6.

  • In general similar to male. Epigynum and vulva as in Figs 6–8. Further, see Lessert (1943) for a detailed description.

  • Type material: 1♂ 1♀ syntypes (examined): D.R. CONGO : Flandria: Leg. R.P. Hulstaert, det. Lessert 1943, no more label data, material badly preserved, male legs separated, left palp removed/missing, chelicerae missing, MRAC 239288; 1♀ syntype, together with 1 palp and 2 chelicerae, legs separated, epigynum dissected (not examined): D.R. Congo: Sankuru: Komi, probably lost, see remarks below.

  • Other material examined: BOTSWANA : Okavango Delta: Shakawe Fishing Camp, 18°25′S 21°53′E, 12.xii.2006. leg. C. Haddad, beating short shrubs, 1♂ (NCA 2007/1088). CÔTE D'IVOIRE: Bingerville: 00°20′S 19°06′E, 1.ii.1963, leg. J. Decelle, 1♂ (MRAC 239297). D.R. CONGO : Bokuma: x.1936, leg. R.P. Hulstaert, 1♀, damaged and in a fragile condition (MRAC 239299). SOUTH AFRICA: KwaZulu-Natal: Ndumo Game Reserve, 26°52′S 32°12′E, 9.i.2002, leg. C. Haddad, grass, sweep net, 1♀ (NCA 2002/599); Tembe Elephant Park, 27°01′S 32°24′E, 8.i.2002, leg. C. Haddad, beating short shrubs, 2♂ 2♀ (NCA 2006/1401).

  • Remarks: The specimens cited in the original description as types are housed in MRAC (239288). The palp and two chelicerae that were originally in MHNG were probably from the aforementioned male syntype. These parts and a single female, probably the female from Komi mentioned in the original description, were loaned some years ago to Pekka Lehtinen (formally of the Zoological Museum, University of Turku, Finland) and never returned (Peter Schwendinger, in litt.). They are now believed lost.

  • Distribution: Botswana, Democratic Republic of the Congo, Ivory Coast, South Africa.

Geraesta hirta Simon, 1889
Figs 9–11, 16

  • Geraesta hirta Simon, 1889: 7, 225, figs 3–4; Benjamin 2011: 16, figs 7f, 39a–e, 40a–f, 41a–f; Ramírez 2014: 223, figs 151a–b, 172f.

  • Geraesta bilobata Simon, 1897: 7, fig. 5.

  • Diagnosis: Males of G. hirta can be distinguished from congeners by the combined presence of the following characters: spiniform C with an acute tip, spoon-like MA with a tapered stalk, and an elongated filiform E that winds 0.5× around the tegulum.

  • Description: See Benjamin (2011).

  • New records: COMOROS: Grande Comore: Tsinimouapanga, Noumamilima, 11°50′S 43°26′E, 780 m, 1.vi.2003, leg. R. Jocqué & D. van den Spiegel, forest, beating, 1♀ (MRAC 239300); Djoumouadjongo, 11°48′S 43°17′E, 268 m, 30.v.2003, leg. R. Jocqué & D. van den Spiegel, forest, 1♀ (MRAC 239296); La Grille, S. de Ivembeni, Ferme GP, 11°27′S 43°20′E, 825 m, 22.xii.1983, leg. R. Jocqué, sieving, 1♂ (MRAC 239301). Madagascar: Toamasina Province: Station Forestière Analamazaotra, administered by Mitsinjo, 0.75 km N of Andasibe, 18°55.783′S 48°24.696′E, 964 m, 31.i–3.ii.2009, leg. C. Griswold et al., general collecting day and night, primary montane rainforest, 1♀ (CAS, CASENT 9035910); Same label data as previous, 1♂ 1♀ (CAS, CASENT 9035911); Same label data as previous, 1♂ 1♀ (CAS, CASENT 9035912).

  • Distribution: Previously known only from Madagascar, recorded from the Comoros for the first time.

Figs 9–16.

(9, 10, 11, 16) Geraesta hirta Simon, 1889 and (12–15) G. congoensis (Lessert, 1943), male from Côte d'Ivoire, MRAC 239297 (12) and syntypes, MRAC 239288 (13–15): (9, 10, 12–14) habitus, dorsal; (11) left palp, ventral view; (15) right palp, ventral view; (16) epigynum, ventral view. Scale bars: (11, 16) = 0.2 mm, (15) = 0.5 mm, (9, 10, 13, 14) = 1.0 mm, (12) = 2.0 mm.

f09_309.jpg

Geraesta octolobata (Simon, 1886), comb. n.
Figs 1726

  • Stephanopis octolobata Simon, 1886: 170 (♀ syntype from MADAGASCAR, deposited in MNHN, but not found; species catalogue card found, but no vial in jar # 1547 mentioned therein).

  • Diagnosis: Males and females of G. octolobata can be distinguished from congeners by the eight dorsal lobes of the opisthosoma, which is reflected in the species name. Further, males can be distinguished by the combined presence of the following characters: C with a short filiform tip, concave MA with a stout stalk and a groove in the apical half, and filiform E slightly longer than the length of the tegulum.

  • Description:

  • Male.

  • Measurements: total length: 5.0; prosoma length: 2.7, width: 2.3. Leg I: femur 3.3, patella 0.9, tibia 3.2, metatarsus 2.6, tarsus 1.2.

  • Prosoma brownish with a prominent triangular-shaped white patch and random dark green/black patches (Figs 17, 18). Opisthosoma with eight whitish dorsal lobes in two rows of four each, blackish with green/black patches medially and laterally. Leg formula 1243, ALE > PLE > PME > AME. AER, PER recurved, eyes on light-brown protuberances, but not touching. Palps as in Figs 2026: single tibial apophysis with serrated tip, cymbium with two dorsal Tr; C broadest at centre, with a short filiform tip; MA concave with stout stalk and groove in apical half; E longer than the length of the tegulum.

  • Female.

  • The female is only known from the original description.

  • Material examined: MADAGASCAR: Antsiranana: R.S. Manongarvio, 17.3 km 218° SW Antanambao, 14°01.35′S 48°28.09′E, 1600 m, 27.x-7.xi.1998, leg. B.L. Fisher, 1♂ (CAS, CASENT 9057555, #1971 MT); Antananarivo: Station Forestière Angavakely, 22 km E Antananarivo, 18°55.06′S, 47°45′E, 1300 m, 8.ix.2001, leg. D. Andriamalala, T. Andriambinintsoa, J.J. Rafanomezantsoa & D. Ubick, low canopy remnant forest, general collecting, 1imm.♀ (CAS, CASENT 9001385).

  • Remarks: The examined specimens fit the description of Simon (1886).

  • Distribution: Endemic to highland forests of Madagascar.

Stephanopis rhomboidalis Simon, 1886

  • Stephanopis rhomboidalis Simon, 1886: 169 (1♂ 1♀ syntypes from MADAGASCAR, should be in the MNHN, but not found; no species catalogue card found).

  • Remarks: This species is considered a nomen dubium as no known Geraesta or Stephanopis species can be unambiguously linked to this name.

Figs 17–23.

Geraesta octolobata (Simon, 1886), males from CASENT 9057555 (17, 20–23) and CASENT 9001385 (18, 19): (17, 18, 19) habitus, dorsal; (20–23) left male palp in ventral (20), retrolateral (21), dorsal (22) and prolateral (23) views. Scale bars: (20–23) = 0.2 mm, (18) = 0.5 mm, (17, 19) = 1.0 mm.

f17_309.jpg

Figs 24–26.

Geraesta octolobata (Simon, 1886), male from CASENT 9057555, left palp in ventral (24), retrolateral (25) and dorsal (26) views. Abbreviations: C — conductor; E — embolus; MA — median apophysis; RTA — retrolateral tibial apophysis; Tr — trichobothrium. Scale bars = 0.2 mm.

f24_309.jpg

ACKNOWLEDGEMENTS

This study was mainly funded by a fellowship from the Alexander von Humboldt Foundation. Additional funding came from the Institute of Fundamental Studies and the Zoological Research Museum Alexander Koenig. Bernhard Huber helped me in various ways during my stay in Bonn. I thank Charles Haddad and the editorial team of African Invertebrates for giving me the opportunity to honour Ansie with this contribution. Two anonymous reviewers made suggestions that considerably improved the manuscript.

REFERENCES

1 

S.P. Benjamin 2011. Phylogenetics and comparative morphology of crab spiders (Araneae: Dionycha, Thomisidae). Zootaxa 3080: 1–108.

2 

J.-C. Ledoux 2004. Araignées de l' île de La Réunion: I. Hahniidae, Ctenidae, Thomisidae et Clubionidae (Araneae). Revue Arachnologique 14: 159–191.

3 

R. de Lessert 1943. Araignées du Congo belge (Troisième partie). Revue Suisse de Zoologie 50: 305–338.

4 

Y.M. Marusik , M.M. Omelko & S.P. Benjamin 2013. The first description of adult female of Borboropactus asper (O. P.-Cambridge, 1884) from Sri Lanka (Araneae: Thomisidae). Zootaxa 3737: 197–200.

5 

N.I. Platnick 2014. The World Spider Catalog. Version 14.5. New York: American Museum of Natural History. ( http://research.amnh.org/entomology/spiders/catalog81-87/index.html; accessed 16/08/2014).

6 

M.J. Ramírez 2014. The morphology and phylogeny of dionychan spiders (Araneae: Araneomorphae). Bulletin of the American Museum of Natural History 390: 1–374.

7 

E. Simon 1886. Espèces et genres nouveaux de la famille des Thomisidae. Actes de la Société Linnéenne de Bordeaux 40: 167–187.

8 

E. Simon 1889. Etudes arachnologiques. 21e Mémoire. XXXI. Descriptions d'espèces et de genres nouveaux de Madagascar et de Mayotte. Annales de la Société entomologique de France 6: 223–236.

9 

E. Simon 1897. Histoire naturelle des Araignées. T. 2, fasc. 1. Paris: Encyclopédique Roret.

Suresh P. Benjamin "On the African Crab Spider Genus Geraesta Simon, 1889 (Araneae: Thomisidae)," African Invertebrates 56(2), 309-318, (1 August 2015). https://doi.org/10.5733/afin.056.0205
Published: 1 August 2015
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