Cladomelea debeeri, Roff & Dippenaar-Schoeman, 2004

Roff, John & Dippenaar-Schoeman, Ansie, 2004, Description of a new species of Cladomelea bolas-spider from South Africa, with notes on its behaviour (Araneae: Araneidae), African Invertebrates 45, pp. 1-6 : 3-6

Cladomelea debeeri sp. n.

( Figs 1–4)

Type material: Holotype female collected at 45 Milliken Road , Pietermaritzburg (29 38'S: 30 28'E), KwaZulu­Natal, South Africa, approx. 600 m above sea level, 12 May 2000, J. Roff (NCA 2003/ 1657).

Etymology: The species name is a patronym in honour of Len de Beer, a friend of the first author, who assisted in the collection of the type specimen.

Diagnosis: The abdomen is triangular and bears prominent tubercles ( Fig. 1) arranged in clusters of five, each on the antero­median corners of the abdomen. Each tubercle bears a tuft of long setae ( Fig. 2 ). In the other three species of Cladomelea , the abdomens are decorated with short, blunt tubercles scattered over the dorsal surface, without tufts of setae. Cladomelea debeeri is distinct in having four short prominent tubercles on the carapace ( Figs 3, 4 ) compared to the three very long and slender tubercles present in the other three species.

Description: Female.

Total length 15.84 mm; carapace length 3.84 mm; abdomen length 12.58 mm (abdomen partly covers carapace); carapace width 3.92 mm; abdomen width 12.0 mm.

Carapace: Yellowish brown, decorated with an intricate dark brown pattern, consisting of medially dark spots and striae; pear­shaped, truncated anteriorly; covered with long white woolly setae; cephalic region slightly raised, bearing a row of strong tubercles (1:1:2); the medial tubercle is the largest with a shorter tubercle in front and a pair of shorter tubercles behind ( Figs 3, 4 ); clypeus yellowish brown with brown spots laterally; chelicerae yellowish brown with dark spots medially and brown markings laterally; sternum creamish white; mouthparts brown, paler around edge; eyes in two slightly recurved rows; anterior median eyes and posterior median eyes on common eye tubercle ( Fig. 4 ); anterior median eyes slightly larger than posterior median eyes; lateral eyes adjacent on shallow tubercles, equal in size; median ocular quadrangle wider than long; cheliceral fang furrow with three teeth on posterior margin and a group of denticles scattered in between; sternum width 1.6 mm, length 1.76 mm.

Abdomen: Creamish yellow; triangular in shape ( Fig. 1); each corner studded with five prominent tubercles ( Fig. 4 ); each tubercle cream at base and dark at apices, bearing a tuft of long white setae ( Fig. 2 ); posterior corner with six tubercles, each bearing hair tufts; spinnerets dark.

Epigynum: Lacks a scape, with only a small rounded lip ( Fig. 5 ).

Legs: Creamish white with dark spiralling bands on femora, patellae and tibiae; metatarsi with longitudinal bands; legs without strong setae but bearing dense long hair­like setae; leg measurements (mm):

femur patella tibia metatarsus tarsus total

I 4.24 1.92 4.0 3.6 0.96 14.72

II 4.40 1.76 4.0 3.3 0.80 14.26

III 2.40 0.96 1.6 1.2 0.56

IV 3.44 1.60 1.12 1.84 0.56

Behaviour:

The spider was first encountered at 07:45 on 8 May 2000. Observations on the spider were made on four consecutive nights thereafter.

Retreat: The spider was first observed hanging from a trapeze­line made about 1.8 m above the soil surface. The threads were attached to a branch of an Azalea bush. When found, the spider was feeding on a moth, which it dropped when disturbed. The spider moved up the trapeze­line to a retreat consisting of two leaves pulled together with a few strands of silk. The spider remained in the retreat throughout the day until the evening (17:44) when it was found hanging from the trapeze­line, below the retreat, busy constructing a bolas­line.

Bolas­line: The bolas­line consisted of a thread constructed of multiple strands of silk, with three sticky droplets adhering to it. Each droplet was approximately 2–3 mm in diameter. First a long silk thread with a single droplet was produced; a slightly shorter thread with a second droplet was then made; a third thread, which was the shortest, with another droplet, was finally made. The end result was a three­strand thread held together with three droplets, positioned one above the other. Observations on two other nights showed that the spider made a bolas­line in the same fashion, but the number of droplets varied from two to three.

Operating the bolas­line: The spider used its fourth leg to hold onto the trapeze­line. The bolas­line was then whirled at intervals, using the second pair of legs. Initially, the whirling happened at intervals of about five minutes, but later became more frequent,

TABLE 1

Comparison of the behaviour of two South African species, Cladomelea akermani and Cladomelea debeeri sp. n.

Cladomelea akermani Cladomelea debeeri sp. n. Hunting site

Generally found on grass stems Collected from tree layer up to 1.8 m above soil surface

Retreat

None. Spider found on grass with legs Found in retreat made of leaves attached curled up around body with silk threads

Activity period

Sunset to about midnight Sunset to sunrise

Bolas­line

Single thread with 1–2 droplet 2–3 threads with 2–3 droplets

Leg involvement

Leg I held straight out and swung back Leg I held straight out and forth

Leg II held bolas­line and acts as the axis Leg II used to hold and whirl the bolas­line around which the body oscillates and bolas rotate

Leg III hold onto trapeze­line Leg III unused

Leg IV hold onto trapeze­line Leg IV hold onto trapeze­line

Whirling of web

Vigorous whirling Less vigorous, erratic whirling with intervals of 1–5 min with intervals of between one to two minutes. The third pair of legs did not seem to be used during the prey­catching process. The spider constructed a new bolas every one to two hours. On the evening of 10 May the spider responded to the noise of a nearby car engine by rapidly increasing the rate of whirling. This suggests that the vibration of a moth’s wings while in flight would elicit a similar response. Except for the first evening, when the spider was observed feeding on a moth, no prey was caught during the observation period. The female was eventually collected and preserved in 70 % alcohol on the 12 May 2000.

Egg sacs (Fig. 6): The female was found with two egg sacs attached to a twig near the spider’s retreat. They were fastened to the twig with irregular silken threads on the lower side and resembled dead leaves. The egg sacs were round (diameter 11 mm), beige, with a very tough outer layer consisting of closely woven silk. One egg sac was manually opened on 15 June but the spiderlings were still underdeveloped. The young spiders (between 150 and 200) emerged from this egg sac on 16 July, clustering close to the cocoon. They dispersed fairly rapidly, some by ballooning, and by 18 June only two or three were left.

In Table 1 the behaviour of the two South African bolas spiders is compared. The behaviour of C. akermani is based on the observations of Leroy et al. 1998, which differ from those of Akerman (1923). The two species differ both in their choice of hunting site and in the construction and handling of the bolas­line.

Figures

Figs 2–5. Cladomelea debeeri sp. n. 2. Abdominal tubercle with tuft of setae. 3. Cephalothorax, anterior view. 4. Outline of body, lateral view. 5. Epigynum. 6. Egg sacs.