Bijdragen tot dl Dierkunde, 55 (1): 125-130 — 1985 Possible species isolation mechanisms in some scolopendrid centipedes (Chilopoda; Scolopendridae) by J.G.E. Lewis Taunton School, Taunton, Somerset TA2 6AD, England the femur of Abstract are seen on Eupolybothrus spp. Various other lithobiid secondary sexual sexual characters in dis- Secondary centipedes are briefly characters have been reviewed by Lewis (1981). cussed and it is that the the suggested spines on prefemora of the described Differences type above are of the last pair of legs in some scolopendrids are used in presumably associated with mating behaviour specific discrimination prior to mating. The hypothesis is in which male and female head discussed with reference of the come together to Scolopendra spp. eastern Mediterranean,north-east Africa and Arabia. to tail, and the antennae and the last pair of legs Where species of Scolopendra with identical The virtually are tapped. morphological adaptations in spinulation on the last legs are sympatric, a large size dif- the males would serve for the femalesto identify ference exists between them. different and sex. It is that in where the species suggested some genera prefemoral have been inhibited. In spines are absent, speciation may the where be absent genus Otostigmus spines may or spine similar in number of other patterns are very a species DIMORPHISM IN SCOLOPENDRIDAE secondary sexual characters have developed. Sexual is also in dimorphism seen the scolopen- INTRODUCTION dromorph family Scolopendridae. In Scolopendra morsitans Linnaeus the dorsal side of the Centipedes not infrequently exhibit secondary prefemur, femur and sometimes the tibiaof the last of is sexual characters. In a number of geophilo- pair legs flattened and there is a promi- each lateral border. morphs the last pair of legs of males are tumes- nent ridge along In and in Porat the cent more densely setose than they are Otostigmus spinosus posterior tergites male Pereira small in the female females. In Pectiniunguis pampeanus bear spines (Lewis, 1982). Coscaron males have dense fine from In & setae Otostigmus (subgenus Parotostigmus) from antennal females from antennal South America and is segment two, Africa, there frequently a three. the inner side of segment In Pectiniunguis argentinensis cylindrical process on the Pereira Coscaron the last of in males & antennal setae are prefemur of the pair legs and in in males and there is dense field of O. males have in shorter a (P.) insignis Kraepelin addition setae on the second antennal segment (Pereira & a large coxopleural process on the 20th pair of In the Coscaron, 1976). mecistocephalid genus legs (figs. 1, 2). Male O. (P.) caudatus Brolemann have Tygarrup from the Himalayas females lack ster- an almost cylindrical posterior nital fields. median last pore process on the tergite (fig. 3). number the tibiae In a of Lithobius species of Some leaf-footed centipedes (Alipes spp.) also the 14th and 15th of swollen and show the pairs legs are a peg-like or cylindrical process on in- bear which side of the of the last of in may a groove posterodorsally ner prefemur pair legs contains males. sometimes a wart-like outgrowth or Such have been well ridge. modifications Neither Alipes nor Parotostigmus show the described by Eason (1973). Similar structures usual spined prefemur of the last pair of legs 126 PROCEEDINGS 6th INTERNATIONAL CONGRESS OF MYRIAPODOLOGY Fig. 1. Dorsal view oftergite 21 and the prefemora ofthe last pair of legs ofOtostigmus (Parotostigmus) insignis (after Attems, 1930). the terminal of the Fig. 2. Ventral view of segments same (after Attems, 1930). Fig. 3. Tergite 21 of O. (P.) caudatus (after Attems, 1930). Fig. 4. Dorsal view of tergite 21 and left last leg of Asanada sokotrana Pocock from Tiptur, India. of the the femur of the left last Fig. 5. Ventral view of segments 20 and 21 same, showing leg. 6. Ventral view of the terminal and of the last of of Fig. segments prefemora pair legs Scolopendra cingulata. Fig. 7. Ventral view of the terminal segments and prefemora of the last pair of legs of Scolopendra morsitans. of the last of valida. Fig. 8. Ventral view of the terminal segments and the prefemur right leg Scolopendra Fig. 9. Dorsolateral view of tergite 21 and the prefemora of the last pair oflegs and prefemur and femur of the 20th leg of the same specimen. 10. Ventral view of the 21st and the of the left last of dalmatica. Fig. segment prefemur leg Scolopendra and the of the last of the and coxopleural process pair spines on prefemur coxopleural process legs tends to be reduced and also lacks spines. of the last pair of legs. The last pair of legs also lacks spines in Asanada Where the prefemur of the last pair of legs and Some of bears (figs. 4, 5) Arrhabdotus. species Cor- spines considerable variation is seen also lack within from another. mocephalus (subgenus Colobopleurus) a genus one species to BIJDRAGEN TOT DE DIERKUNDE, 55 (1) - 1985 127 Thus Scolopendra cingulata Latreille usually has two ventral spines and four dorsolateral spines ventral (fig. 6 shows a specimen with only one spine on each prefemur). Scolopendra morsitans has three of three usually rows spines ventrally and five dorsolateral spines (fig. 7). Scolopendra valida Lucas similarly has three rows of three but there about spines ventrally (fig. 8) are ten dorsolateral There spines (fig. 9). are, moreover, spines at the end of the dorsal surface of the prefemora of legs 20, 19 and sometimes 18. In L. Koch Scolopendra dalmatica C. there are two rows of 3-5 spines ventrolaterally and 10-18 spines ventromedially and dorsomedially (fig. 10), that is between 30 and 40 spines in all. The function of these has spines not been ex- plained although a number of observations made have been on the uses of the last pair of legs. Jangi (1961) suggested that the last pair of of served legs Scolopendra as posterior antennae. In act Alipes spp. they as stridulatory organs and in Asanada spp. they are readily autoto- mised and perform distracting wriggling movements when detached. The autotomised last legs of Rhysida nuda togoensis Kraepelin make a squeaking noise (see Lewis, 1981, for details). The last of used in pair legs are the ritualised Map. 1. The distribution of five scolopendrids in north- meeting reactions of scolopendrids. When two east Africa, the eastern Mediterranean and Arabia. each Scolopendra cingulata meet, attempts to S.Scolopendra morsitans, S. valida, * S. cingulata, ■ the grasp of the trunk of the posterior region canidens, □ Trachycormocephalus mirabilis. other with its last pair of legs (Klingel, 1960); only very occasionally do the animals bite each other. Similar behaviour has been observed in Cormocephalus anceps anceps Porat by Brunhuber Newport and Trachycormocephalus mirabilis Porat which is of related (1969). a species Scolopendra to the The on the of the last canidens spines prefemur legs group (Lewis, unpublished). In most directed backwards and is are it therefore areas only two or three species occur: cingulata, unlikely that they are used to facilitate gripping morsitans and canidens in Egypt, cingulata and for which they should be directed forward. The canidens only in Israel, morsitans, valida and T. most likely explanation of their function is that mirabilis in the central Sudan but only valida and used in discrimination they are specific prior to mirabilis in the eastern Sudan and Ethiopia. If this the then would mating. is case one not Four species occur in the mountainousregion of have the north-east expect sympatric species to same spine Iraq, namely, cingulata, valida, canidens and T. S. morsitans arrangement. mirabilis. occurs in 1 shows the distribution of the and from Map five species Euphrates valley apart an im- of Scolopendra in the eastern Mediterranean, precise locality in southern Ethiopia, it is north-east Africa and S. limited land below 1000 Arabia, namely to m throughout the S. S. morsitans, valida, cingulata, S. canidens entire area. 128 PROCEEDINGS 6th INTERNATIONAL CONGRESS OF MYRIAPODOLOGY Map 2 shows Wiirmli's (1980) data for the canidens distribution of species of the group: Scolopendra clavipes C. L. Koch, S. dalmatica, S. canidens, S. oraniensis (Lucas) and S. cretica At- tems. In these species the number and arrange- the the ment of spines on coxopleural process and prefemur of the last pair of legs is extremely similar. S. clavipes is distinguished by the clavate shape of the last leg pair; it is the most distinct of these species. Of the other species the last in both in pair of legs is glabrous sexes dalmatica canidens but have brush-like hairs and long on Fig. 11. Ventral view of the terminal segments and the tarsus I and II of the last pair of legs in males in prefemora of the last pair of legs of Scolopendra canidens. cretica and oraniensis. Neither dalmatica or for mirabilis. Fig. 12. The same Trachycormocephalus canidens, nor cretica or oraniensis occur together. of in which I am only aware two cases species canidens and T. mirabilis identical last S. have similar spine with virtually legs are sympatric. the of the last of These morsitans and what patterns on prefemora pair legs are Scolopendra Jangi 8-13 (figs. 11, 12), but whereas canidens has (1959) came to regard as Scolopendra amazonica the laeta Haase in (normally 11 or 12) spines on coxopleural (Bucherl) and S. morsitans and S. T. mirabilis has 5. These Australia. In both of the process, normally two cases one species pair other is than the in India the species are largely allopatric. The species much larger other: max- have distinct from canidens imum size of amazonica is 65 and that of S. spine patterns very mm and in and mirabilis and from each other.