Pasilobus dippenaarae, Roff & Haddad, 2015

Roff, John & Haddad, Charles R., 2015, Pasilobus dippenaarae sp. n. (Araneae: Araneidae), a new species of cyrtarachnine spider from South Africa, with a key to the Afrotropical species, African Invertebrates 56 (2), pp. 445-445 : 448-452

Pasilobus dippenaarae sp. n.

Figs 6–16

Etymology: The species is named for Dr Ansie Dippenaar-Schoeman, in recognition of her significant contributions to the taxonomy and biology of African spiders.

Diagnosis: Pasilobus dippenaarae sp. n. is related to P. insignis , but can be distinguished by the presence of five pairs of tubercles on the anterior margin of the abdomen as opposed to seven (excluding the anterolateral pair), the median eyes on a small mound (absent in P. insignis ), and the presence of several tubercles on the femora, patellae and tibiae of all of the legs (e.g. Fig. 12 ), which are only on the tibiae I and II of P. insignis . It shares with P. mammosa the small mound on which the median eyes are situated, but has fewer tubercles along the anterior margin of the abdomen (five as opposed to seven). Male unknown.

Description:

Female (holotype, NMSA 26881).

Measurements: CL 3.20, CW 3.40, AL 4.95, AW 10.15, TL 9.65, SL 2.90, SW 3.05, AME–AME 0.18,AME–ALE 0.59, ALE–ALE 1.63, PME–PME 0.25, PME–PLE 0.70, PLE–PLE 1.86, MOQAW 0.57, MOQPW 0.51, MOQL 0.46.

Length of leg segments: I 2.90 + 1.40 + 2.10 + 1.90 + 0.65 = 8.95; II 2.90 + 1.38 + 1.95 + 1.70 + 0.65 = 8.58; III 2.00 + 0.75 + 1.15 + 1.03 + 0.55 = 5.48; IV 2.80 + 1.00 + 1.80 + 1.32 + 0.58 = 7.50.

General appearance as in Figs 6 , 10 . Carapace yellow-brown, with black mottled markings; slightly broader than long, eye region narrowed, thoracic region round, posterior margin concave; surface coarsely rugose, naked except for short white setae around margins, few scattered setae dorsally, and longer setae on clypeus. Median eyes situated on small rounded mound, lateral eyes on weak tubercle; AER strongly recurved from above, medians much larger than laterals; AME separated by distance equal to their diameter; AME separated from ALE by distance approximately three times AME diameter; clypeus height equal to AME diameter; PER strongly recurved, medians slightly larger than laterals; PME separated by distance slightly less than double their diameter; PME separated from PLE by distance eQual to five times PME diameter.

Chelicerae yellow-brown, with scattered short setae on anterior of paturon, longer along mesal margin; promargin with three teeth, proximal tooth smallest, distal tooth largest; retromargin with large subequal proximal and distal teeth, with small tooth between them; field of small denticles between tooth rows. Endites almost sQuare, yellow-brown, paler prolaterally; serrula and maxillar hair tuft distinct; labium subtriangular, with tongue-like anterior margin; nearly twice as broad as long; yellow-brown, cream distally; endites and labium both with scattered long and short black setae. Sternum shield-shaped, anterior margin concave; yellow-brown, with faint black mottling and scattered long black setae.

Legs yellow-brown, with paler proximal and median bands on femora; surface rugose, particularly femora to tibiae, with several tubercles, covered in short setae ( Fig. 12 ); femur I with three prominent and two smaller prolateral tubercles; femur II with one prominent and two smaller prolateral tubercles; femur III with one prominent dorsal tubercle; femur IV with three (right) or two (left) prominent dorsal tubercles; patellae all with distal tubercle, larger on I and II than on III and IV; tibia I with one prominent and two smaller prolateral tubercles, and three small dorsal tubercles; tibia II with two prominent prolateral and two small dorsal tubercles; tibiae III and IV without tubercles; all tibiae with several dorsal and lateral trichobothria, longer on III and IV; metatarsi I and II with small basal tubercle, none on III and IV; all tubercles with slightly thicker, longer white setae than surrounding leg setae.

Abdomen much broader than long, surface smooth; anterior margin with five pairs of small tubercles, followed by pair of large anterolateral tubercles; medially, small pair of tubercles immediately behind first anterior pair on dorsal surface; two pairs of large tubercles on lateral margins; two pairs on posterior margin, followed by trapezoid lobe with paired lateral tubercles; anterior surface of abdomen with two rows of sigilla, first with eight pairs of small yellow-brown sigilla, second rows with median sigillum and six pairs of larger orange-brown sigilla; dorsum with median and five pairs of sigilla anteriorly, more or less between paired tubercles; from anterior median sigillum four pairs of large sigilla, arranged in diamond, with several pairs of small sclerites between them; two pairs of large sigilla along posterolateral margin; single median and two pairs of lateral sigilla above posterior lobe; several pairs of large orange-brown sigilla on lateral and posterior sides of abdomen. Dorsum dark grey, darker along midline, with paired transverse cream markings medially ( Figs 6 , 10 ); large pair of anterolateral tubercles yellow-brown; posterolateral margin with pair of black patches; posterior end of dorsum cream, marking extending onto posterior lobe, which has two narrow lateral black markings; abdomen dark grey laterally, wrinkled and black ventrally; venter with many small sclerites; tracheal spiracle slit-like, in front of small triangular cololus.

Epigyne with ovoid yellow-brown anterior sclerite, immediately in front of short narrow scape, and paired lateral sclerites covering booklungs; scape directed somewhat anteriorly ( Figs 13–15 ); copulatory openings antero-prolaterally within sclerotised oval ridges, just anterior to epigastric furrow; copulatory ducts forming two loops, doubling back in single channel before entering oval spermathecae ( Fig. 16 ).

Variation (paratype female, NMSA 26882).

Measurements: CL 3.4, CW 3.6, AL 6.0, AW 14.2, TL 9.6.

Specimen gravid or recently fed, abdomen swollen, tubercles less distinct than holotype ( Figs 8 , 11 ). Abdominal colouration in living specimen bright orange-brown, markings as for holotype.

Male. Unknown.

Holotype ♀, with 2 egg sacs (sacs not collected): SOUTH AFRICA: KwaZulu-Natal: Hilton College Nature Reserve, Gwen’s Stream , 29°28'49.06"S 30°16'53.58"E, leg. J. Roff, 17.vi.2014 (NMSA 26881, type no. 3394).

Paratype ♀, with < 5 egg sacs (1 egg sac collected): SOUTH AFRICA: KwaZulu-Natal: Hilton College Nature Reserve, Gwen’s Valley , 29°28'59.92"S 30°17'03.94"E, leg. J. Roff, 28.v.2006 (NMSA 26882, type no. 3395) .

Additional material observed but not collected: SOUTH AFRICA: KwaZulu-Natal: Cumberland Nature Reserve, uMgeni River , 29°30'43.92"S 30°31'26.10"E, leg. J. Roff, vi.2007, <5 egg sacs; Hilton College Nature Reserve, Gwen’s Stream , 29°28'41.27"S 30°16'52.83"E, leg. J. Roff, vi.2010, <5 egg sacs; KwaZulu-Natal National Botanical Garden , 29°36'28.09"S 30°20'50.77"E, leg. J. Roff, iii.2005, 3 egg sacs; Pietermaritzburg, Boughton , 29°36'05.30"S 30°20'11.78"E, leg. J. Roff, iv.2011, 1♀ with egg sacs; Pietermaritzburg, Boughton , garden, 29°36'16.83"S 30°19'48.58"E, leg. J. Roff, i.2012, 1 subadult ♀ .

Distribution: Only known from six localities in the vicinity of Pietermaritzburg in KwaZulu-Natal, South Africa ( Fig. 17 ).

BIOLOGICAL OBSERVATIONS

This species was first observed in a wooded suburban garden in Boughton, Pietermaritzburg during March and April 2001. The initial observation was of several egg cases constructed on a washing line.Approximately 20 m away, next to another egg case ( Fig. 4 ), a mature female spider was observed on the upper surface of a leaf of Cestrum laevigatum , approximately 1.5 m above ground ( Figs 6, 9 ). It had made a thin covering of silk threads on which it was sitting. Observations were made sporadically over several days, during which time the spider moved to a new location about 2 m above the ground in the leafy branches of a Citrus × limon . At the new site it was observed to construct a catch-web resembling the one illustrated in Robinson and Robinson (1975).

Females and egg sacs were subsequently observed on several occasions in the vicinity of Pietermaritzburg. Based on this data, there was no preference for foliage types or tree species with regards to foraging microhabitats of spiders and sites for egg sac production. Most observations were made between 1 and 2.5 m from the ground (Table 1). All specimens were observed and/or collected during summer and autumn, and no records exist for winter and spring thus far.

The two specimens collected (holotype and paratype) were kept alive for several days for observation. They were only active nocturnally, and did not construct catch-webs.All spiders observed in the field were on the upper surfaces of leaves, fully visible during the day, strongly resembling bird droppings. The thin scattering of silk threads on the leaf surface surrounding the first observed specimen increased its resemblance to a bird-dropping.All egg sacs observed had a similar shape to the one pictured ( Fig. 9 ): a moreor-less truncated teat shape and mottled dark brown colour, suspended 5–10 cm from the plant substrate. In habitat the egg sacs are hard to distinguish from the dead leaves around them. In three localities, sacs were found several metres apart, suggesting that the spiders move periodically as egg-laying adults. This may serve to reduce predation and parasitism of the eggs. Such behaviour has been noted in Cladomelea akermani Hewitt, 1923 by the first author (personal observation).

Figures

Figs 6–9.Pasilobus dippenaarae sp. n., photographs of (6–8) the habitus of live females and (9) egg sac:(6) female from Boughton, Pietermaritzburg; (7) holotype and (8) paratype from Hilton College Nature Reserve; (9) egg sac suspended in web between foliage of shrubs, arrow indicating female sitting on leaf nearby (Boughton, Pietermaritzburg). Photographs: (6, 8, 9) by J. Roff; (7) by D. von Hoesslin.

Figs 10–13. Digital microscope photographs of Pasilobus dippenaarae sp. n.: (10) habitus of holotype; (11) same, paratype; (12) dorso-prolateral view of femora I and II, arrows indicating large and small tubercles; (13) paratype, ventral epigyne.Abbreviations:AS – anterior sclerite; LS – lateral sclerite; SC – scape. Scale bars: (10, 11) = 5 mm; (12, 13) = 0.5 mm.

Figs 14–16.Pasilobus dippenaarae sp.n.paratype,epigyne in ventral (14), posterior (15) and antero-dorsal views (16).Abbreviations:AS– anteriorsclerite;LS – lateral sclerite;SC – scape.Scalebar = 0.5 mm.

Fig. 17. Distribution of Pasilobus dippenaarae sp. n. in KwaZulu-Natal, South Africa.

Figs1–5.Habitus illustrations ofAfrotropical Pasilobus species,taken from their original descriptions:(1) P. laevis Lessert,1930;(2) P.antongilensis Emerit,2000; (3) P.capuroni Emerit,2000;(4) P.mammosus (Pocock, 1899); (5) P.insignis O. Pickard-Cambridge,1908.All figures reproduced with permission.