Courtship behavior and copulation in Tengella radiata (Araneae, Tengellidae)

2008·2.6 MB·English

by  Gilbert Barrantes

2008. The Journal ofArachnology 36:606-608
SHORT COMMUNICATION
Courtship behavior and copulation in Tengella radiata (Araneae, Tengellidae)
Gilbert Barrantes: Escuela de Biologi'a, Ciudad Universitaria Rodrigo Facio, Universidad de Costa Rica, San Pedro, San
Jose, Costa Rica. E-mail: [email protected]
Abstract. The first description of the courtship behavior and copulation is provided for Tengella radiata (Kulczynski
1909). The male courts the female by rocking his body and vibrating his abdomen. These behaviors seem to induce the
female to moveout from herretreat onto thesheet and incline herbody to facilitateintromission. Thefemale hasan active
role during thecourtship: strumming the tunnel and sheet threads, apparently inducing the male to increase the frequency
and intensity ofhis courtship. Palpal insertion is extremely short. The female terminates the copulation by lunging at the
male.
Keywords: Courting, sexual selection, funnel web spider
Tengellaradiata(Kulczynski 1909) hasawidedistribution in Costa apparent attack toward him, or adopting the copulatory position
Rica where it inhabits mature and secondary wet forests and coffee (described below). In total, thecourtship behaviorand copulationsof
plantations from 50 to 1500 m elev.(Wolff 1977; Santana et al. 1990, T. radiata lasted 57 min in onepair(5 copulations) and nearly90 min
pers. obs.), but it is, nevertheless, unknown outside of this small (9copulations) in thesecond pair. In bothcases the femaleeventually
country. Its web consists ofa large, horizontal sheet with an upper expelled the male from the web.
tangle that contains some cribellate threads and a tunnel at the When the male walked directly toward the tunnel opening, he
“interior” section of the sheet (Santana et al. 1990; Eberhard et al. stopped suddenly as the female began to strum the threads of the
1993; Eberhard & Pereira 1993). Spiders rest near the tunnel opening sheet with more or less alternate movements of her palps (Fig. 1).
during the day. Strumming occurred in bouts of up to 20. During a strumming
The sexual biology ofthis spider is completely unknown. In nature movement the female first extended both palps anteriorly and then
males occasionally co-inhabit webs with adult females (W.G. flexed first one and then the other posteriorly, snagging some threads
Eberhard pers. comm), and I have occasionally observed males near ofthe sheet with the tip ofthe palps. These sheet threads were pulled
or on the sheet ofpossibly adult females. Here I describe for the first upward (visible in some video records) until they snapped free,
timethecourtshipbehaviorandcopulation ofT. radiataandcompare possibly due to the tension. The palpal movements gave the
these behaviors to those of some species within families of the impression of scratching the sheet surface rather than twanging
Tengella''s sister groups lycosoids and agelenoids (Coddington 2005). particular threads.
The family is of interest because it is a cribellate member of the The female strumming movements apparently induced the male to
Lycosoidea. stop, at least momentarily. The male then responded by rocking his
Courtship behavior and copulation oftwo pairs of T. radiata were body vigorously in antero-posterior direction (Fig. 2). He stood with
filmedusingadigitalvideocamera Sony DCR-VX 1000(30frames/s). all his legs on the sheet and shook the sheet visibly as he moved
Both females were virgins raised from eggs in captivity and (occasionallylegs I were lifted while rocking). The rockingmovement
maintained in plasticboxes(30 X 18 X 1 1 cm)wheretheyconstructed was produced primarily by the antero-posterior movement of the
theirwebs. One female was paired with one male that was also raised male’s body rather than by bending his legs and occurred in bouts of
incaptivityfromdifferentparents. Thesecond femalewaspairedwith 3-5 rocking movements (n = 12). The male also frequently vibrated
an adult male collected in the field. Male pre-copulatory and hisabdomenonceortwicejust beforeaboutofrockingmovements(5
copulatory courtship behavior and copulation are defined as in out of8 bouts in which illumination and angle were favorable). The
Eberhard & Huber (1998). Male courtship refers to those behaviors female frequently stopped strumming the sheet (5 out of7 sequences
that induce the female to respond in a way that favors the male's where both male and female were in focus); nearly immediately the
reproduction (Eberhard 1996). Copulation consists of all genitalic male began to rock. Ifthefemale remainedmotionless aftera rocking
contact between a particularmale-female pair, includingthe insertion bout, the male often advanced a few millimeters toward her (2 of 8
of the embolus into the epigynal opening. It finishes when the pair instances). However, in most cases the female began again to strum
separates from the copulatory position. Drawings were traced from the sheet as the male approached her, inducing him to stop and
video images. Spiders and egg sacs were collected near San Jose, resume courtship. It seemed that in these cases the male rocked his
Costa Rica; voucher specimens were deposited at the Museo de body more vigorously before moving again toward the female that
Zoologia, Escuela de Biologia, Universidad de Costa Rica. remained inside but near the tunnel opening. In one instance the
The first reaction ofthe male when placed on the female’sweb was femalemoved slowlyoutofthetunnelandstoppedandstrummed the
to walk on the sheet, more or less randomly at first and then toward sheet before continuing toward the male. The male rocked his body
thetunnel openingwherethefemale rested. Followingthismovement, and advanced toward the female but she moved back a few
courtship and copulation can be roughly divided into three millimeters and then darted at him in an attacking position (first
consecutive phases seen in both pairs: courtship by male, while the legs slightly raised and directed forward and chelicerae spread). The
femaleisin thetunnel, with the result that thefemalemovesoutofthe male moved rapidly backward nearly 4 cm then began to rock his
web tunnel; male courtship once the female is out on the sheet, body again while the female returned to the tunnel.
presumably to induce the female to adopt the copulatory position; In both pairs, after several separate bouts ofrocking by the male
and copulation. The female responded to male courtship by either (12 in one pair and 17 in the other), the female moved out of the
sending vibratory signals through the web threads, launching an tunnel,ceased strummingthesheet,andallowed themaletoapproach
606
BARRANTES—SEXUAL BIOLOGY OF TENGELLA RADIATA 607
—
Figures 3, 4. Position ofmale and femaleprevious to and during
insertion. 3. The female lays on her right side as the male walks over
her body. 4. Male inserting his left pedipalp (embolus) in the left
opening ofthe female’s epigynum.
movements ofthe male’s abdomen, and were similar to the abdomen
bobbing movement ofLeucauge (Eberhard & Huber 1998). The pre-
copulatory and copulatory courtship behaviors of a male after
— subsequentcopulations on opposite sides were similar (e.g., flubs: 19-
Figure 1. Strumming movements of the female’s palps on the 15-16; three subsequent copulations). The extremely short insertions
sheet during courtship. Arrows show the sequence of the palps’ were successful as one of the females produced fertile eggs. The
movements: dots- initial position, dashed- subsequent position, solid- insertions seemed to be ipsilateral (by the position of the female’s
final position. epigynum and male’s palp), although 1 could not be completely
certain due to the dark color ofthe epigynum and male’s palp.
her. The male moved over the female’s body so that they faced Thefemaleterminated copulation when she began tomove herlegs
opposite directions, and as he did so she inclined her body laterally to stand on the sheet after a single successful insertion ofthe male’s
(Fig. 3), with herepigynum exposed (copulatory position). From this palp (n = 5) or after several unsuccessful insertion attempts of the
position the male repeatedly contacted the female’s epigynum with male’s palp (n = 4) (I could not differentiate unsuccessful insertion
one palp (Figs. 3, 4), while his other palp was held in front of his attempts from flubs). In one case the male remained over the female
body.Themale’sextended palpmoved rapidlytotouch theepigynum and she darted toward him in an attacking position. The female’s
wbriitehfldyrawandcycltehen= w0i.t11hdr±ew0.(0m2esan, ndur=ati3o7n). oTfheesxetenmdo-vceomnteanctts- athtattacpkospirtoivoonkededhiamnaetxt3reorme4lycrmapfirdombahcerk.waAfrtdermotvheemfeemnatlebyhatdheenmdaelde
apparently correspond to “flubs” observed in other species (Watson the copulation, the male began a new approach with a sequence of
1991; Stratton et al. 1996; Huber 1998; Eberhard & Huber 1998). On pre-copulatory courtship behaviors. The courting male stopped
two occasions where the complete sequences were observed, the male
frequently to pass his palps and sometimes his legs through his
made 17 and29 flubs before the palpengaged with the epigynum and mouthparts before approaching her again; occasionally the male
rttheoemdaohicanheeamdeaxtiponafdnlosactiheodan dlwauasrstiendfgi0na.tl3hl8eysien(nft±liart0ee.d1.i6,nsTnehret=ioin5n)s.e(rTnthieo=nsha2w)e.imtahOtnohdaotehcmrhaea-e crbhuoebdlbiyceedtroahewi.asrDpdualrtpihsengaogpeapaiocnshsittnetehwseidmsehaelaeestatahpfetperrmoaaglcreho,owmatihlenkgefdehmioasvleperalihpnescrliwniaetndhdhhheiers
occasions (2 in one pairand 1 in the other, where theangle and focus immediately began to contact her epigynum with his other palp.
were appropriate), the male was observed to move his abdomen up Successive inclinations and insertions were on opposite sides (n = 12)
and down in possible copulatory courtship movements. These except when the male failed to insert hispalp in the previousattempt.
movements were slower than the pre-copulatory courtship vibratory
In suchcasesthenextmaleapproach occurredonthesamesideofthe
female side that he had approached previously. The female was
apparently responsible for the alternation of sides in subsequent
copulations; it was clear on two occasions that she began to incline
her body before the male could contact her.
Having copulated, the female did not necessarily accept the male
the next time heapproached her. On several occasions(10 in one pair
and 4 in the other) the male stopped his approach as she began to
strum the sheet, and he restarted his rocking courtship behavior.
Neither male charged his palps with sperm during the courtship,
indicating that males charged their palps before encountering a
female.
The male’s pre-copulatory rocking and abdominal bobbing
movements during copulation may reduce the female’s aggression
and induce her to cooperate and use his sperm to fertilize her eggs
(Eberhard 1996; Stratton et al. 1996; Eberhard & Huber 1998; Peretti
— et al. 2006). It is possible that these movements inform the female of
Figure 2. Two partial sequences (a and b) of male-female the male’s quality. For example, one of the females of this study
courtship. Black boxes- female strumming movements. Empty boxes- immediately lunged at and expelled from the web a small adult male
male rocking movements. Dashed boxes- male moving toward the (ca. 15% shorter than the males studied) that 1 had previously placed
female. on her web.
608 THE JOURNAL OF ARACHNOLOGY
The strumming behavior of the female, her ability to expel males (D. Ubick, P. Paquin, P.E. Cushing & V. Roth, eds.). American
with her attacks, and assumption ofa distinctive acceptance posture, Arachnoiogical Society.
all clearly show her active role in mating (Peretti et al. 2006). This Eberhard, W.G. 1996. Female Control: Sexual Selection by Cryptic
behavior possibly servesthe femaleasacriterion for maleselection as Female Choice. Princeton University Press, Princeton, NewJersey.
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his courtship behavior after he detects a female strumming. As in Eberhard, W.G. & B.A. Huber. 1998. Courtship, copulation, and
many other spiders, there was no indication of males being able to sperm transfer in Leucauge mariana (Araneae, Tetragnathidae)
force females to cooperate (Huber 1996; Eberhard & Huber 1998). with implications for higherclassification. Journal ofArachnology
It is possible to compare some aspects ofthecourtship behavior of 26:342-368.
T. radiata with that of species ofother related families: Agelenidae, Eberhard, W.G. & F. Pereira. 1993. Ultrastructureofcribellatesilk of
Lycosidae and Pisauridae (Coddington 2005). In all these families, nine species in eight families and possible taxonomic implications
diinrcelcutdiionng (TN.ierlasdeinat1a9,32m;alMeisllmerou&ntMiflelmearle1s98f7a;ciHnegbeitnsthete aolp.po1s9i9t6e; (taAtriadnaeea,e:HAypmoacuhriolbiidiadea,e,StDiepihniodpiiiddaaee,, DTeesnigdeallei,daDei)c.tynJioduaren,alFilios-f
Stratton et al. 1996; Huber 1998; but see Bruce & Carico 1988). Arachnology 21:161-174.
However in T. radiata the male’s courtship induces the female to Eberhard, W.G., N.I. Platnick & R.T. Schuh. 1993. Natural history
incline herbody to expose herepigynum, and thus his ventral surface and systematics of arthropod symbionts (Araneae; Hemiptera;
touches (or nearly so) the ventral surface ofthe female, while in wolf Diptera) inhabiting webs ofthe spider Tengella radiata (Araneae,
spiders the male’s ventral surface touches the dorsal surface of the Tengellidae). American Museum Novitates No. 3065:1-17.
femaleand themale’s pedipalp reaches the female’sepigynumaround Hebets, E.A., G.E. Stratton & G.L. Miller. 1996. Habitat and
the side of her abdomen. In at least some lycosids (Stratton et al. courtship behavior ofthe wolfspider Schizocosa retrorsa (Banks)
1996) and in several agelenids (Huber 1998) males also flub (“scrape” (Araneae, Lycosidae). Journal ofArachnology 24:141-147.
in Stratton et al. 1996) repeatedly prior to insertions. Copulations Huber, B.A. 1998. Spider reproductive behaviour: a review of
involve ipsilateral palpal insertion on alternating sides in all families Gerhardt’s work from 1911-1933, with implications for sexual
(Stratton et al. 1996). Alternating insertions with only a single selection. Bulletin ofthe British Arachnoiogical Society 11:8-91.
expansion of the hematodocha also occurred in Rabidosa spp. Miller, G.L. & P.R. Miller. 1987. Lifecycleandcourtship behaviorof
(Lycosinae) (Stratton et al. 1996). Female attack behavior similar to the borrowing wolfspider Geolycosa turricula (Treat) (Lycosidae).
thatofT. radiataoccursin onelycosid (Miller& Miller 1987)and one Journal ofArachnology 15:385-394.
pisaurid (Arnqvist 1992). Many of these behaviors are possibly Nielsen, E. 1932. The Biology ofSpiders: With Especial Reference to
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evolution of courtship behavior in Tengella and related families. Peretti, A., W.G. Eberhard & R.D. Briceno. 2006. Copulatory
Particularly, theinformation oncourtship behaviorofagelenoids, the dialogue: femalessingduringcopulation to influencemalegenitalic
sister group ofTengellidae and lycosoids, is very important to trace movements. Animal Behaviour 72:413-421.
the evolution ofthe courtship behavior in these groups ofspiders. Santana, M., W.G. Eberhard, G. Bassey, K.N. Prestwich & R.D.
I thank William G. Eberhard, Gail Stratton and two anonymous Briceno. 1990. Low predation rates in the field by the tropical
reviewers for many helpful comments on the manuscript and the spider Tengella radiata (Araneae: Tengellidae). Biotropica 22:305-
Universidad de Costa Rica for financial support.
309.
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