Plebs mitratus Joseph & Framenau, 2012

Joseph, Mathew M. & Framenau, Volker W., 2012, Systematic review of a new orb-weaving spider genus (Araneae: Araneidae), with special reference to the Australasian-Pacific and South-East Asian fauna, Zoological Journal of the Linnean Society 166 (2), pp. 279-341 : 333-335

PLEBS MITRATUS ( SIMON, 1895) COMB. NOV.

( FIG. 34 )

Araneus mitratus Simon, 1895: 805–806 ; Bonnet, 1955: 545; Sherriffs, 1918: 60–61, 63–64; Sherriffs, 1919: 241–242, 244.

Types: Holo-/ syntype (s) of Araneus mitratus Simon, 1895 . Unspecified number of females from ‘montagnes de l’India’ ( Simon, 1895: 805) (= mountains in India; no specific locality given). Not present in MNHN, not examined.

Neotype of A. mitratus Simon, 1895 . ♀ Kerala ( India), Aana Mudi Shola National Park , Idukki District, 10°11 ′ 21 ′′ N, 77°11 ′ 17 ′′ E, 24.vii.2010, M. J. Mathew, C. S. Jayadevan, tropical montane wet temperate forests, 1875 m a.s.l. ( WAM T109510 ). Designated here (see Remarks section below for justification).

Other material examined: Twenty-seven females and one juvenile from three records (Appendix S1).

Diagnosis: Plebs mitratus differs from the only other Indian congener, P. himalayaensis , in female scape morphology. In P. mitratus , the scape ( Fig. 34E ) is smooth in contrast to a wrinkled scape in P. himalayaensis ( Tikader, 1982) . Additionally, the scape is kinked in the middle in P. himalayaensis , whereas it is straight in P. mitratus .

Description

Female: Based on WAM T109510 from Aana Mudi Shola National Park, India. Carapace light yellow, patches of dark brown pigmentation along the lateral margins and a central patch of dark pigmentation extending from fovea anteriorly ( Fig. 34A ); glabrous with the exception of sparse white setae mainly in cephalic area and in a narrow band along lateral margins; fovea Y-shaped. Chelicerae yellow-brown, a band of dark pigmentation running along the dorsal surface reaching up to the mid-region; a few black setae mainly in the apical half; four promarginal teeth and three retromarginal teeth. Sternum dark brown, a weak cover of brown bristles. Abdomen dorsally glabrous, with a sparse cover of white and brown setae; distinct humeral humps present; dorsum covered with off-white pigmentation, interspersed with a greenishbrown folium and red pigmented spots ( Fig. 34A ), lateral margins covered with green pigmentation. Venter with greenish-brown pigmentation ( Fig. 34B, D ); weakly covered with brown bristles. Spinnerets brown. Legs yellow with black annulations, moderately spined; leg formula 1> 4> 2> 3. Epigyne scape elongated, widest at the base. ( Fig. 34E ); spermathecae elongate kidney-shaped ( Fig. 34F ).

Dimensions: total length (excluding chelicerae) 5.75. Carapace length 2.38, width 2.23, height 1.15. Eyes: AME 0.15, ALE 0.13, PME 0.13, PLE 0.12, AME–AME 0.13, AME–ALE 0.27, PME–PME 0.04, PME–PLE 0.35, PLE–ALE 0.02, MOQ width front 0.35, MOQ width back 0.33, MOQ length 0.35, eye group width 1.08. Sternum length 1.00, width 0.88. Abdomen length 4.38, width 3.25. Palp: femur 0.67, patella + tibia 0.97, tarsus 1.15, total 2.79. Leg I: femur 2.73, patella + tibia 3.94, metatarsus 2.12, tarsus 0.85, total 9.64. Leg II: femur 2.42, patella + tibia 3.33, metatarsus 1.82, tarsus 0.61, total 8.18. Leg III: femur 1.70, patella + tibia 1.82, metatarsus 1.27, tarsus 0.48, total 5.27. Leg IV: femur 3.03, patella + tibia 3.33, metatarsus 2.12, tarsus 0.79, total 9.27.

Variation (range): TL 5.50–6.13; CL 2.13–2.50; CW 2.00–2.25; AL 4.13–4.88; AW 3.00–3.38; N = 5.

Male: unlnown.

Remarks: Araneus mitratus was listed by Simon (1895: 805–806), who very briefly circumscribed the somatic and genitalic morphology of this species, albeit in combination with another similar species that he had named from India earlier, Araneus minutalis Simon, 1889 ( Simon, 1889) . This description constitutes A. mitratus as available species-group name according to ICZN Article 12.1. Sherriffs (1918), as first reviser of the species, listed ‘ Araneus mitratus (Sim.) ’ from the Nilgiris mountains in southern India, thereby providing some more detailed distribution data for the species. In addition to mature females, he also described an immature male in detail. This booklet ( Sherriffs, 1918), originally published in Madras (copy seen by V. W. Framenau in ZMUC), was later ( Sherriffs, 1919) re-published in the Annals and Magazine of Natural History, Series (9) in London with minor alterations to photographs and illustrations (copy seen by V. W. Framenau in WAM). Bonnet (1955) only referenced the later publication from 1919, not the original from 1918. Araneus mitratus was listed by Bonnet (1955), but not by Roewer (1942) and subsequent catalogues, including the most recent World Spider Catalog ( Platnick, 2012).

The MNHN apparently does not hold the type material of A. mitratus (C. Rollard, pers. comm.) and we consider it here lost. However, we accept Sherriffs’ (1918, 1919) concept of A. mitratus as a species occurring in southern Indian mountain regions and redescribe the species here based on an examination of Sherriffs’ (1918, 1919) original material (ZMUC12902) and conspecific material from southern India collected more recently by the senior author. In accordance with ICZN Article 75.3.1, we here designate a neotype for A. mitratus to clarify the type locality of the species, which is doubtful based on the original description by Simon (1895: 805: ‘montagnes de l’Inde’). This designation is also necessary to explicitly avoid confusion with P. himalayaensis , a congeneric species that is found in northern mountainous regions of India.

We here propose the transfer of this species to Plebs , P. mitratus ( Simon, 1895) comb. nov., based on somatic and genitalic morphology, in particular the distinct ventral coloration of the abdomen with inverted light U-shaped pattern and additional spots anterolateral of the spinnerets ( Fig. 34B, D ) (synapomorphy of Plebs ; Fig. 3 ). In contrast to all other Asian Plebs , the species is redescribed here in detail as no illustrations or detailed descriptions are available for P. mitratus .

Distribution: Southern India.

Life history and habitat preferences: Although adults have been observed throughout the year, the peak occurrence is from September to January. The spiders prefer a temperate climate and are generally restricted to higher altitudes (above 1000 m). Webs can generally be found in low grassy vegetation in open pockets of forests especially on the edges of forest trails. Webs are often decorated with stabilimentum (M. M. Joseph, pers. observ.).

Figures

Figure 3. Phylogenetic hypothesis for Plebs within a taxon sampling of Australian ‘eriophorine’ orb-weaving spiders (Araneidae) (length = 114, consistency index = 0.38, retention index = 0.72). Full circles indicate unambiguous synapomorphies and open circles homoplasious character state changes. Character numbers (above circles) and states (below circles) as in Table 1. The topology only shows unambiguous character state changes. Bremer support values are given in circles below branches.

Figure 34. Plebs mitratus comb. nov. A, B, female from Aana Mudi Shola National Park, India (WAM T109510). A, dorsal view; B, ventral view. C–F, female from Nilgiris, Tamil Nadu, India (ZMUC 12902). C, dorsal view; D, ventral view; E, epigyne, ventral view; F, epigyne, dorsal view). Scale bar = 2.0 mm in A-D; 0.5 mm in E; 0.2 mm in F.