RlPITUk SQUAMATA: SERPENTES: VIPERIDAE CROTALUS DURISSUS Catalogue of American Amphibians and Reptiles. body has 18-35 brownish or blackish diamond-shaped dorsal n blotches, usually with lighter centers, except in many individuals McCranie, J.R 1993. Cmtalus durissus. from southern South America in which the center is not noticeably lighter than the rest of the blotch. The blotches are usually outlined Crotalus durissus Linnaeus by one row of paler colored scales. Posteriorly, the blotches tend to Neotropical Rattlesnake become shorter, wider, paler in color, somewhat obscure, and merge with the primary lateral blotches. The primary lateral blotches lie Cmtalus Durissuc Linnaeus, 1758:214. Type-locality, -America," re- below the lateral points of the dorsal diamonds anteriorly. stricted tonJalapa,Veracruz, Mexico" by SmithandTaylor(1950: Paravertebral stripes that begin on the head posterior to and above 348), but not a good choice as the Veracruz population shows the eyes usually extend about 1-4 head lengths onto the neck. The some differences from those of the other populations of this paravertebral stripes can be poorly defined in some specimens from subspecies (see Klauber, 195260-61). Typespecimen original- northeastern Mexico or may extend less than one head lenmh onto ly in the Claudius Grill Suriname collection;later sent to the Zo- the neck in animals fromno&eastern and central Brasil. ~cu~ellation dlogiska Museet, Uppsala Universitet, Uppsala, Sweden, but is as follows: 25-33 scale rows at midbodv. all keeled exceot for the now lost (Klauber, 197234). See Remarks (1). lowest 1-3 rows on each side; 159-196 vktrals in males, 1&5-195in Cmtalopborur Durissus: Houttuyn, 1764313. females (C. uniwlor, if considered a subspecies of durissuc, would Umcmtalon Durirnrs: Fitzinger, 1843:29. lower the limits to 155 and 163, respectively); 22-34 subcaudals in Caudisona durissa: Cope, 1861:120.The first use ofthiscombination males, 18-31 in females; 11-18 supralabials; 12-20 infralabials. The that actually applied to this species. rostra1 usuallv is slinhtlv hinher than wide. The internasals and Caudbona durircuc: Sumichrast, 1881:270. prefrontals a& usuily 'paiGd and in contact medially, although Cmtalus akvissu: Richardson, 1972:lOl. Lapnu. snakes from the Pacific versant of Mexico northwest of the Isthmus of Cm&Jlusdu~:Jacobson, 1986:167. Lapnu,not seen,f&Smith Tehuantepec tend to have the prefrontals subdivided into smaller and Smith (1993:518). scales, as do occasional specimens from throughout the species range. Anteriorly 2-5 (usually 2 or 3) intersupraoculars are present. Content. Twelve subspecies are currently recognized: The parietal and occipital regions are covered by small keeled scales, durissus, ccatavella, collilineatus, culminatus, cumanensis, except in some specimens from northeastern Mkico in which larger, dtyina., mamfwnris, mnrimq tedJcus, tobnanrs, higonicus, irregular, vestigial parietals are present. The first supralabial usually and turbcan. See Remarks (2). is in broad contact with the prenasal, although a row of foveals may prevent this contact in specimens from southwestern Mexico. Each DeBnition and Magno8lr. Cmtalus durircuc is a large side of the head has 1-8 loreals (usually 2 or 3, except in snakes from species, with large adult males of some populations reaching about southwestern Mexico, which usually have 4 or 5). 1800 mm TL. However, several South American populations contain Cmtalus durissus is the only species of rattlesnake occurring members that are stunted, with many adults not exceeding about throughout much of its large geographical range. Only in Mkico 1000 mmTL. The species usually has a conspicuous vertebral ridge north of the Isthmus of Tehuantepec, in the savannas and alluvial that is best developed in large adults, especially on the anterior plains of the southwestern portions of the Venezuelan states of portion of the body. Individuals from northeastern Mkico tend to Anzoategui and Monagas, and on Aruba Island off the northern coast m have a ledweloped ridge. The dorsal ground color can be brown, of South America doesthe range of durissur overlap orapproachthat reddish brown, grayish brown, yellowish brown, yellowish gray, of other species of Cm&JIus (but see Remarks t21 concerning the yellowish olive, greenish gray, pale bluish gray, or nearly black. The South American 'species" C. uniwlor and C. qrandis). Cmtalus Figwe. Cmtalus durirnrs totonacuc from pine-oak woodlands 5.6 km WSW El Lobo, Querhro, Mexico (photograph by L. Porras). CL durissus approaches or overlaps the ranges of four large Mexican species (ahnr, basiliscur, momolaurrr, and scutulatus) north of the Isthmus of Tehuantepec. CmtaIus durissus can be distinguished Descriptions. An excellent morphological and color de- from each of these species by having conspicuous paravertebral scription of C. durissus is incampbell and Lamar (1989). Other good n stripes. Cmtalusdurisnrs can be further distinguished from C. abvx morphological and colordescriptionsare inCei(19861, Gloyd (1%0), and C. scutulatus by having a strongvertebral ridge (no strong ridge), Klauber (1952), Lancini and Kornacker (19891, Roze (19661, a nearly uniformly colored tail (strongly contrasting dark and pale Vanzolini et al. (1980), and Wilson and Meyer (1985). Osteological rings), and usually having 4-6, except 4-10 on the Pacific versant, features were described by Brattstrom (19641, and those of the scaie; in the inte&~-~kfro&l area (usually 8 or more). ~mtalk hemipenis by Klauber (1972) and Vellard (1946). durissus can be further distinrmished from C. basilism where their ranges overlap in southwestek Michoackn by having 27-33, usually .mwtrations. This is one of the most profusely illustrated 29, scale rowsat midbody (24-29, or usually 27), 170-182 and 173-188 species of all American amphibians and reptiles and the following ventrals in males and females, respectively (178201 and 184-206, citations are by no means exhaustive. Color illustrations of several respectively), and a nearly uniform tail color (gray with gray subspecies are in Campbell and Lamar (1989, Hoge (19661, and crossbands moderately evident). mica1 C. du- can be distin- Mehrtens (1987). Other good color illustrations are in Abuys (1987), guished from C. molossus by having a distinct vertebral ridge, in Alvarez del Tom (1983), Amaral (1977), Bolafios (19841, Campbell addition to having paravertebral stripes. However, individuals of and Brodie (1992), Carrizo (1988), Cei (1986), Chaves et al. (1990), durissus in northeastern Mexico, where the rangesofthe two species Coborn (19911, CNZ(1987), Duvernoy (1836-18491, Freiberg (19821, overlap, resemble C. rn0hw.s in tending to loose the distinct Freiberg and Walls (1984), Gans (19751, Hoge and Roman-Hoge vertebral ridge and in having poorlydefiied paravertebral stripes (198la), Jahn (19831, Klemmer (19631, Kundert (1974,19841, Lancini (Fig. 1). Campbell and Lamar (1989) have suggested that these two and Kornacker (1989), Levy (1983, as 'Fer-de-lance"), Mercado speciesmight hybridize innortheasternQuer&aro. ?he northeastern (1975), Moonen et al. (1979), Obst et al. (1988), Perez-Higareda and Mexican population of durisnrs can usually be distinguished from Smith (1991), Perez-Santos and Moreno (19881, Perkins (19741, Rob- mob in having paired parietal and occipital stripes (absent or erts (19841, RogC and Sauvanet (1987), Roze (19701, Schmidt (19901, obscure and ~oorlvdefied),a dark urefrontal crossbar (entire Schmidt and Inger (1957), Schnitzler (1987), and Villa et al. (1988). dorsum of headanterior to suboculars ukally dark), andthe primary Good black and white illustrations of several subspecies are in Glenn lateral blotches lvin~below the lateral wints of the dorsal diamonds and Straight (19821, Gloyd (1940), Harrisand Simmons (1972,197&), anteriorly (dokl bTotches more ofte; coalesced with the primary Hoge (1966), Hoge and Romano (19731, Hoge and Roman-Hoge lateral series). South American C.durhu canbe distinguished from (1981b), and Klauber (1956, 1972). Good black and whine illustra- C. vegmndis and C. unicolor by having well-defiied dorsal dii- tionsalsooccur inthe following papersthat arecitedelsewhere in this rnonds and paravertebral neck stripes (diamonds and stripes ob- account:Allenand Neil1 (1957),Amaral(1927b, 1977),~rrnstrongand scured by numerous scattered white-tipped scales in vegmndis and ~urphy(1979), Freiberg (19821, Gloyd and Kauffeld(19401, Harris diamonds and neck stripes faded and largely absent in adult and Simmons (1978b), Hoge and Romano-Hoge (1981a), Klauber Map 2. The SouthAmericandistribution of Cmtalurdurissuc. Open circlesmarktype-localities,solid circles otherrecords. The type-localities of the subspecies catcauella, collilinaahrs, and dryinas are too imprecise to be plotted (the type-locality restriction for catcauelka is invalid and that for dryinas is arbitrary). Some solid circles may represent several localities. ?he subspecific status of the many isolated Amazonian records is unknown. See McCranie (1984,1986) for the ranges of C. wgrandis and C. unicolor,both of which are considered by some authors to be subspecies of C. durissuc. (1952), Lancini and Kornacker (19891, Roze (19661, Sage and em and central Michoadn, Mexico, to the western portion of the Capredoni (19711, Snchez-Herrera et al. (1981), Sandner Montilla Meseta Central in westcentral Costa Rica, with apparently continu- (1975, 19801, Stanek (19621, and Tinoco (1978). Other illustrations ous extensions into the Atlantic drainages