M. Brian Traw.
A revision of the neotropical orb-weaving spider genus Scoloderus (Araneae: Araneidae).
Psyche 102:49-72, 1995.

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A REVISION OF THE NEOTROPICAL ORB-WEAVING SPIDER GENUS SCOLODERUS (ARANEAE: ARANEIDAE) Museum of Comparative Zoology
Harvard University
Cambridge, Massachusetts 02 138*
More than one-fourth of the spiders examined for this revision were collected since the neotropical genus Scoloderus was revised in 1976. Thirteen names have been proposed for what appear to be five valid species (Scoloderus cordatus, S. gibber, S. nigriceps, S. tuberculifer, and S. ackerlyi). These species are distinguished by the presence or absence of abdominal humps on the female, the shape of the median apophysis of the male palpus, and the shape of the scape of the female epigynum. Abdominal coloration and pat- tern are highly variable and unreliable for identification. One new species, Scoloderus ackerlyi, is described on the basis of a single, unique female from Belize.
The orb-weaving genus Scoloderus (Simon, 1887) consists of five species, one of which is new. The genus is primarily neotropi- cal in distribution, although individuals have been recorded as far north as Georgia, United States and as far south as Rio Negro, Argentina.
Scoloderus spiders, as adults, spin very tall, rectangular webs. The most detailed information about Scoloderus web structure is known from observations of S. tuberculifer in Colombia (Eberhard, 1975). At the base is an orb-web. Radii on the upper half of the orb-web extend vertically up to 1.0 m forming a long rectangle. *Correspondence: Section of Ecology and Systematics, Corson Hall, Cornell Uni- versity, Ithaca, NY 14853. Email: mbt @ cornell.edu. Manuscript received 30 March 1995.
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50 Psyche 1~01. 102
Spiders spin their webs in the late evening and tear them down each morning. These webs have been hypothesized to facilitate the capture of moths. When moths strike the upper part of the web, they tumble down, losing scales along the way. By the time they reach the bottom the moths have lost so many scales that they stick to the web (Eberhard, 1975; Stowe, 1978). The first Scoloderus species described were placed in Hypoph- thalma (Taczanowski, 1879), having the type species H. deplanata Taczanowski. Simon (1887) found the name Hypophthalma preoc- cupied and determined that the species placed by Taczanowski in Hypophthalma actually belonged in two genera. The species con- sidered in this paper were ones that were placed in a new genus Scoloderus (Simon, 1887), having the type species H. cordata. The other species were placed in the genus Hypognatha Gukrin- Mkneville, having the type species H. feisthameli (=H. scutata) (Simon, 1895). Early descriptions of Scoloderus species (including S. cordatus, S. tuberculifer, S. nigriceps, S. normalis, S. hybus, S. birabeni, S. intermedius, and S. nigrocellatus) were based solely upon female specimens. One species, S. eresimorpha, was described on the basis of a single immature male (Taczanowski, 1879). Only 5'. americana and S. gibber were described with information on males. Unfortunately, the male holotype of S. gib- ber has since been lost and was not available for this revision. Abdominal pattern and coloration were important criteria for these early descriptions.
Upon discovering that abdominal coloration and pattern were highly variable in Scoloderus, Levi (1976) synonymized all Scoloderus names under either S. cordatus or S. tuberculifer. Levi's classification was based on differences in the structure of the scape of the female epigynum and the median apophysis of the male palpus. The difficulty of placing the many recently collected specimens of Scoloderus has prompted this revision. Scoloderus gibber (0.P.-Cambridge) and S. nigriceps (0.P.-Cambridge) are resurrected from Levi's (1976) synonymization. Scoloderus gibber and S. nigriceps are distinguished by the genitalia, as well as by the presence or absence of abdominal humps. Additionally, this study includes information on the structure of the male palpus of Scoloderus based upon examination under a scanning electron microscope. The palpal structure of Scoloderus



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has previously eluded accurate description due to the small size and transparency of some parts.
METHODS AND MATERIALS
Specimens were examined primarily under a dissection micro- scope for this revision. Eye sizes, distances between eyes, and clypeus height were all recorded in units of anterior median eye diameter (AME). The techniques for measuring and drawing spider body parts followed a standard method for spider genus revisions (Levi, 1993). The male palpi of four species were examined through both a dissecting microscope and a scanning electron microscope. The SEM photographs were of right palpi. In this paper, SEM photographs are printed in reverse to render them comparable to illustrations of left palpi. Specimens for this revision were generously loaned from the following collections:
AD
AMNH
BMNH
CAS
FSCA
IRSNB
MACN
MCN
MCZ
MEG
MUSM
A. Dean Collection, Texas A and M University, Col- lege Station, Texas, United States
American Museum of Natural History, New York, United States; N. Platnick, L. Sorkin
British Museum (Natural History), London, Great Britain; P. Hillyard
California Academy of Sciences, San Francisco, United States; C. Griswold, W. J. Pulawski, D. Ubick Florida State Collection of Arthropods, Gainesville, Florida, United States; G. B. Edwards
Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium; L. Baert
Museo Argentine de Ciencias Naturales, Buenos Aires, Argentina; E. A. Maury, C. L. Scioscia Museu de CiEncias Naturais, Porto Alegre, Rio Grande do Sul, Brazil; E. H. Buckup
Museum of Comparative Zoology, Cambridge, Mass- achusetts, United States; H. W. Levi
M. E. Galiano; Buenos Aires, Argentina
Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Lima, Peru; D. Silva



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52 Psyche [VOI. 102
MZSP
Museu de Zoologia da Universidade de SZio Paulo, S5o Paulo, Brazil; P. Vanzolini, L. Neme, J. L. M. Leme
PAN
Polska Akademia Nauk, Warszawa, Poland; A. Slo- jewska, E. Kierych
I thank H. W. Levi for suggesting this project, providing helpful comments, and offering encouragement throughout. L. Leibensperger's logistical support and advice were greatly appreci- ated. L. Leibensperger, H. W. Levi, W. Piel, N. E. Gift, and two anonymous reviewers offered suggestions that improved the manu- script. This revision benefited greatly from illustrations drawn by H. W. Levi (Figs. 1-7, 11-14, 19, 20, 22, 23, 29-33) and his descriptions of previously examined types. Scanning electron microscopy was conducted at Harvard's Museum of Comparative Zoology with the help of R. L. Pinto.
Scoloderus Simon
Scoloderus Simon, 1887: 187. Type species by original designa- tion Hypophthalma cordata Taczanowski. The generic name is masculine.
Diagnosis. Scoloderus is close to Wixia (Levi, 1993) but has a bulging, helmet-shaped carapace (Fig. 2). The genus Carepalxis (Levi, 1992a) is also closely allied and has a bulging carapace, but one that is distinguished by two prominent knobs. Scoloderus species lack these knobs, although S. cordatus has two slight, angular projections on top of the bulge (Fig. 1). The pedicel of Scoloderus is generally attached to the posterior third of the abdomen (Fig. lo), unlike Carepalxis and Parawixia (Levi, 1993). However, pedicle attachment can be located more closely to the middle of the abdomen, as in S. cordatus (Fig. 2). The lip of the median apophysis of the male palpus (L in Fig. 7) is not exagger- ated in size as in Wixia (Levi, 1976) and Ocrepeira (Levi, 1993). Palpus of Scoloderus lacks the paramedian apophysis and general complexity of palpi in related genera Parawixia (Levi, 1992b) and Wixia (Levi, 1993). Scoloderus spiders are small (maximum total length, 4.5 mm) in comparison to species in the genus Carepalxis (maximum total length, 15.5 mm). The height of the Scoloderus



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carapace is an apomorphy. Other apomorphies include the attach- ment of the pedicel at the posterior third of the abdominal ventral region (Fig. lo), and a clypeus height of approximately two diame- ters of the anterior median eyes (Fig. 9). Description. Ocular quadrangle wider behind than in front (Fig. 1). Width of carapace behind posterior lateral eyes about 74 to 87% of width of thorax in females, 68 to 78% in males. Anterior and posterior margin of chelicerae with four and three teeth respec- tively. Epigynum of Scoloderus a lightly sclerotized, smooth plate with a lobe (Fig. 4). Lobe of epigynum shorter than half the width of basal plate. Coxa I of males with a hook protruding from its dis- tal margin. Tibia I1 of males thicker than tibia 1 with 5 to 10 macrosetae. Webs much longer than wide with orb at the base. Radii on the upper half of the orb-web extend vertically to form a rectangular ladder (Eberhard, 1975).
Note. The following parts of the median apophysis are used in identification: inner margin (IM in Fig. 7), lip (L in Fig. 7), spine (S in Fig. 16), and distal rim (DR in Fig. 7). The lip of the median apophysis is the area between the inner margin and the distal rim. Species differences. The species of Scoloderus are quite vari- able and often difficult to separate. Females are distinguished by the presence (Figs. 19, 28) or absence (Figs. 2, 10) of abdominal humps. The posterior scape of the epigynum can be reduced to a crescent (Figs. 4, 12), semicircular (Fig. 21), or narrow and pro- truding (Figs. 30, 39). Females have either a notched (Fig. 1) or flat (Fig. 9) surface at the top of the carapace hump. Males are sep- arated based on the shape of the lip of the median apophysis (L in Fig. 7). The lip of the median apophysis can either be broadly semicircular (Fig. 7), narrow (Fig. 25), or broadly rectangular (Fig. 33). The median apophysis can have a pointed distal tip (S in Fig. 16) or one that is rounded (Figs. 7, 25, 33). Distribution. All species come from tropical and subtropical America.
Key to females of Scoloderus species
1.
Scape of epigynum narrow with parallel
sides (Figs. 30, 39) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Scape of epigynum semicircular (Figs. 12, 21) or reduced to a crescent (Fig. 4) . . . . . . . . . . . . . . . . . . .3



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Width of epigynal scape at base roughly
one-third of width of basal plate at
attachment (Fig. 30); Mexico, Central and South America. (Map. 2) ............... .tuberculifer Width of epigynal scape less than
one-fifth of width of basal plate at
attachment (Fig. 39); Belize (Map. 2) ......... .ackerlyi Abdomen with paired humps (Figs. 19, 20) and shaped like a shield; United States, Mexico, Caribbean Islands (Map. 2) ........ .nigriceps Abdomen never with dorsal humps (Fig. 2); abdomen round and dark; legs often ringed; Mexico, Central and South America (Map. 1) ........ .4 Scape of epigynum broadly rounded (Fig. 4); carapace bulge often notched (Fig. 1) ........ .cordatus Scape of epigynum semicircular and
protruding (Fig. 12); carapace bulge
without notch (Fig. 9)
..................... .gibber
Key to males of Scoloderus species
The male of S. ackerlyi is not known
Palpus with median apophysis lip wide,
semicircular in shape (L in Figs. 7, 16); abdomen dark gray to green; clypeus
height greater than two diameters of anterior ....
median eyes; Mexico, Central and South America .2
Palpus with median apophysis lip narrow, rectangular in shape (Figs. 25, 33); abdomen white; clypeus height less than two diameters of anterior median eyes ......................... .3 Distal rim of median apophysis of palpus with a spine (S in Fig. 16) ................... gibber Distal rim of median apophysis of palpus without spine (DR in Fig. 7) ............... .cordatus Lip of median apophysis of palpus at
least two times longer than wide (Fig. 25); abdomen often with dorsal black stripe;
United States, Mexico, and Caribbean
islands (Map. 2) ........................ .nisriceus



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Lip of median apophysis of palpus less
than two times as long as wide (Fig. 33); abdomen with dark pigmented region on
dorsum; Mexico, Central and South
America (Map. 2) . . . . . . . . . . . . . . . . . . . . .tuberculifer Map 1. The distribution of Scoloderus cordatus and Scoloderus gibber.



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Map 2. The distribution of Scoloderus nigriceps, Scoloderus tuberculifer, and Scoloderus ackerlyi.
Scoloderus cordatus (Taczanowski)
Figures 1-8; Map 1
Hypophthalma ? cordata Taczanowski, 1879: 129, pi. 2, fig. 41, 9. Female holotype from Amable Maria [Tarma Prov., Depto. Junin], Peru, in PAN, examined and illustrated by H. W. Levi (unpublished).
Hypophthalma ? eresimorpha Taczanowski, 1879: 130, pi. 4, fig. 8, d'. Juvenile male holotype from Amable Maria [Tarma Prov., Depto. Juni'n], Peru, in PAN, examined and illustrated by H. W. Levi (unpublished).




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Scoloderus cordatus: -Simon, 1887: 187. First placement of cor- datus in Scoloderus.
Carepalxis normalis Keyserling, 1892: 53, pi. 2, fig. 42, 9. Female holotype from Taquara, Rio Grande do Sul, Brazil, in BMNH, examined and illustrated by H. W. Levi (unpublished). Note: The question marks before the specific names are those of Taczanowski and probably refer to the doubtful placement in Hypophthalma.
Description. Female from Cuyabeno, Ecuador. Carapace dark brown. Chelicerae dark brown, darker distally. S ternum dark brown. Legs light brown. Abdomen round with white spot inside a blue-gray pigmented region on dorsum, giving the spider the appearance of a bird dropping. Sides of abdomen green-brown. Venter of abdomen, blue-gray. Posterior median eyes 1.3 anterior median eye diameters (AME), laterals 0.6. Anterior median eyes 1.0 AME apart, posterior median eyes 2.0 AME apart. Anterior and posterior median eyes 5.0 AME from laterals. Clypeus height 2.5 AME. Carapace hump notched (Fig. 1). Carapace very hairy (Fig. 2). Dorsum of abdomen without humps (Figs. 2, 3). Total length 3.6 mm. Carapace 1.6 mm long, 1.4 wide, 1.2 high. Ster- num length 0.7, width 0.8. First femur 1.3 mm, patella and tibia 1.3, metatarsus 0.8, tarsus 0.4. Second patella and tibia 1.2, third 0.8, fourth 1.2.
Male from Cuyabeno, Ecuador. Coloration as in female. Poste- rior median eyes 1.3 diameters of anterior medians, laterals 0.7. Anterior median eyes 1.0 AME apart, posterior medians 2.0 AME apart. Anterior and posterior median eyes 6.5 diameters from later- als. Clypeus height 4.0 AME. Abdomen round. Carapace with dense hair, without notch. Total length 2.3 mm. Carapace 1.3 mm long, 1.0 mm wide, and 0.9 mm in height. Sternum length, 0.5; width, 0.5. Median apophysis 0.1 mm long. First femur 1.0 mm, patella and tibia 1.2 mm, metatarsus 0.7, tarsus 0.4. Second patella and tibia 0.9 mm, third 0.5, fourth 0.8. Variation. Adult female total length 2.9 to 3.6 mm; width of carapace 1.2 to 1.7. Male total length 1.5 to 2.9 mm; width of cara- pace 1.0 to 1.4 mm. Legs sometimes ringed darker brown. Dorsum and sides of abdomen with variable patterns and coloration in both sexes.




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58 Psyche [VOI. 102
Diagnosis. Lip of median apophysis of male semicircular (L in Fig. 7), distal rim lacks spine of S. gibber (Fig. 16). Female is very difficult to distinguish from S. gibber female. The scape of S. cor- datus is shorter in length and more broadly rounded (Fig. 4) than that of S. gibber (Fig. 12). See diagnosis section of S. gibber description for a further comparison. Reliable identification of female S. gibber specimens requires the presence of males. Natural History. Specimens collected in night sweeps of vegeta- tion (B. Malkin, AMNH). Found in grass and scrub (G. B. Edwards, FSCA). A silken pouch containing 18 eggs was found in Loreto Province, Peru (G. B. Edwards, FSCA). Specimens Examined. MEXICO Jalisco: 6.7 km N Autlan, Mine Rd, 7 July, 1984, 9 (J. B. Woolley, AD); 24 km SW of Aut- lan, 15 July, 1983, 9 (P. K. Kovarik, T. L. Harrison and J. C. Schaffner, AD). Veracruz: Jalapa, 6 July, 1963, 9 (D. Bixler, MCZ). PANAMA Panama: Pipeline Road, 8 km NW Gamboa, 7 August, 1983, Q (H. W. Levi, MCZ). COLOMBIA Putumayo: Buena Vista, 23-29 July, 1972, 0, 9 (W. Eberhard, MCZ). SURINAM Marowijne: Anapaike Village at Lawa River, 8-29 November, 1963, 9; Benzdorp at Lawa River, 6 November, 1963, 0, $ (both B. Malkin, AMNH). ECUADOR Napo: Rio Puyo 900 m, 1 April, 1941, C? (W. Clarke, AMNH); 18 April, 1958, 9 (R. W. Hodges, MCZ). Sucumbi'os: Tarapoa, 23 June - 1 July, 1988, 9; Cuyabeno, Napo bridge between Tarapoa and Tipishca, 30 July, 1988, 0, $ (both W. Maddison, MCZ). Pichincha: 4 km NE of Pedro Vicente Maldonado, 9-12 July, 1988, 9 (W. Maddison, MCZ); W Cayambe 2300 m, 7 June, 1965, Q (L. E. Pefia, MCZ). Los Rios: Rio Palenque, 15 February, 1979, 9 (L. Burnham, MCZ); 14 March, 1982, C? (Y. Lubin, MCZ). PERU Loreto: Rio Manatee, 18 July, 1989, 8; Explorama Lodge 80 km NE Iquitos, 16-20 July, 1989, C? (both G. B. Edwards, FSCA). Hudnuco: Tingo Maria, 2 1, 29 October, 1946, 9; 26 December, 1946, C? (all J. C. Pallister, AMNH); 23 September, 1954, C?, 9; 26 October, 1954, $ (both E. S. Ross, CAS); 10, 29 November, 1954, 9 (both E. S. Ross, E. I. Schlinger, CAS); 43 mi E of Tingo Maria, 5 Octo- ber, 1954, $ (E. S. Ross, E. I. Schlinger, CAS). Ucayali: Ivita, Rio Neshuya, 2 July, 1986, 0, Q; 14 July, 1986, 9; 26 July, 1986, C? (all D. Silva, MUSM); Madre de Di'os, Zona Reservada Tam- bopata, trocha, 30 July, 1987, $ (D. Silva, MUSM), Puerto Mal- donado, 16-23 April, 1947. Q (J. C. Pallister, AMNH). BRAZIL



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Amapd: Serra do Navio, June, 1966, Q (M. E. Galiano, MEG). Pard: Belh, Fazenda Velha, July, 1970, 8, 9; Belem, August 1971, (7 (M. E. Galiano, MEG); 8 August, 1962, 9 (K, Lenko, MZSP); Rio Gurupi, Uma, 2-30 May,
1963, $ (3. Malkin,
AMNH). Ronddnia: Fazenda Rancho Grande NE Cacaulandia, Figures 1-8. Scoloderus coniaius (Taczanowski). 1-6, female. 1, eye region and chelicerae. 2, lateral. 3. dorsal. 4-6, epigynum. 4, ventral, 5, posterior. 6, lateral. 7, 8, left male palpus,
Scale lines, 1 mm; genitalia 0.1 mm.
Abbreviations, DR, distal rim. E, embolus. IM, inner margin. L, lip.



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60 Psyche 1~01. 102
2-15 December, 1990, 0, Q (G. B. Edwards, FSCA). Bahia: Fazenda Matiapa Camacan, 16 October, 1978, Q (J. Santos, MCN). Goias: Pirapitinga Piren6polis Goias, 23 June, 1942, Q (F. Lane, MZSP). Rio de Janeiro: Nova Igua~u, 7 September, 1961, 9; Represa Rio Grande, February, 1976, 0, Q; Mangaratiba, Febru- ary, 1976, d', Q; Silva Jardin, August, 1975, d' (all M. Alvarenga, AMNH). S6o Paulo: Caraguatatuba, 16 November, 1942, Q (B. Scares, MZSP); Juquia, Poco Grande, 23 March, 1951, 0; 21-26 July, 1949, d' (both F. Lane, MZSP); Marsilae, 12 March, 1967, 9 (P. Biasi and F. Lane, MZSP); Osasco, 26 October, 1941, 9; 28 November, 1943, 9; Municipio de Itu, Fazenda Paud Alho, 2 February, 1959, Q (both F. Lane, MZSP); Boraceia, 9-15 February, 1949, Q (D. Silva, MZSP). Rio Grande do Sui: Aqua Belas Viamiio, 13 September, 1984, 9; Cauela, 3 1 December, 1973, d'; Garruchos Siio Borja, 7 December, 1975, 0; Irai, 20 November, 1975, d', Q; Montenegro, 20 December, 1977, Q; Passo do Bugio Butia, 13 May, 1982, Q; Passo Fundo, 12 October, 1985, 9; Salto do Yucuma, 16 January, 1985, 0, Q (all A. A. Lise, MCN); Fazenda Recanto de Figueira Arroio dos ratos, 1 August, 1986, d'; Montenegro, 7 July, 1977, <?; Vila Oliva, 5 January, 1976, Q (all E. Buckup, MCN); Vila Oliva, 15 January, 1974, Q (F. Meyer, MCN); Guaiba, 25 December, 1988, C? (A. Bonaldo, MCN); Tgrejinka, Jaquera, 19 October, 1967, C?, 9 (P. Biasi, MZSP). PARAGUAY Alto Parand: SE of Nararyal, 18 August, 1988, Q (L. E. Pefia, AMNH); Tatiyupi Reserve, 1984, 9; Itabo Reserve, 5 June, 1984,
C?, Q (both L. Baert, IRSNB).
ARGENTINA Misiones: Monte Carlo, l3Om, 5 December, 1965, (Giaschi, AMNH); January, 1966, 0, Q (M. E. Galiano, MEG); Eldorado, 11 September-15 November, 1964, Q (A. Kovacs, AMNH); November, 1970, Q (M. E. Galiano, MEG); Parque Nacional Iguazu, Arroyo Yacui, January, 1966, Q; Decem- ber, 1972, 0, Q (both M. E. Galiano, MEG); N Wanda, 12 July, 1988, Q (L. E. Pefia, AMNH). Rio Negro: El Bolson area, 1965-1966, C?, Q (A. Kovacs, AMNH).




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Scoloderus gibber 0. P.-Cambridge
Figures 9-17; Map 1
Scoloderus gibber 0. P.-Cambridge, 1898: 282, pi. 36, fig. 4, 0,Q. Female syntype from Bugaba, Panama, in BMNH, examined and illustrated by H. W. Levi (unpublished). F. P.-Cambridge, 1904: 521, pi. 5 1, fig. 8, 9. Petrunkevitch, 19 11: 386. Roewer, 1942: 872. Bonnet, 1958: 3955.
Scoloderus birabeni Mello-Leitilo, 1945: 242. Female holotype from Puerto Victoria, Misiones Province, Argentina, in Museum of La Plata, examined and illustrated by H. W. Levi (unpub- lished). NEW SYNONYMY.
Scoloderus intermedius Gerschman de Pikelin and Schiapelli, 1948: 13, figs. 14-17, Q. Female holotype from Santa Maria, Misiones Province, Argentina, in MACN, examined by M. B. Traw. NEW SYNONYMY.
Synonymy. Scoloderus birabeni and S. intermedius are both included in S. gibber because both lack tubercules on the abdomen (Fig. 11) and have an epigynum with a protruding scape (Fig. 12). Description. Female from Depto. Madre de Dios, Peru. Cara- pace, chelicerae dark brown. Sternum, coxae light brown. Legs light brown, ringed dark brown. Dorsum of abdomen mottled gray- green; sides white. Venter of abdomen blue-gray. Posterior median eyes 1.0 diameters of anterior median eyes (AME), laterals 0.7. Anterior median eyes 1.0 AME apart, posterior median eyes 1.6 AME apart. Anterior and posterior median eyes 4.5 AME from lat- eral eyes. Clypeus height 2.3 AME. Carapace very hairy, hump without notch (Fig. 9). Dorsum of abdomen without humps (Fig. lo), Total length 3.3 mm. Carapace 1.6 mm long, 1.4 wide, and 1.1 high. Sternum length 0.9 mm, width 1.3. First femur 1.6 mm, patella and tibia 1.7, metatarsus 0.8, tarsus 0.5. Second patella and