Mecistocephalidae, Bollmann, 1913

Published, First, 2007, The Mecistocephalidae of the Japanese and Taiwanese islands (Chilopoda: Geophilomorpha), Zootaxa 1396, pp. 1-84 : 73-76

Key to the species of Mecistocephalidae of the Japanese and Taiwanese islands

For anatomical terminology see Material and methods (clypeal ratio, plagulae, pore­like sensilla, spine­like sensilla) and Figure 54 (spiculum, buccae, plagulae, insulae).

1 Number of leg­bearing segments invariantly 41. Spiculum invariantly absent. Claw of the second maxillae either present (e.g. Figs. 12, 34) or not (e.g. Figs. 4, 20).......................................................................2

­ Number of leg­bearing segments 45 or more. Spiculum either present or not. Claw of the second maxillae invariantly present. ..................................................................................................................................... 5

2 Two clypeal plagulae, separated by a mid­longitudinal areolate stripe. Coxosternum of the first maxillae either divided by a mid­longitudinal suture or undivided. Telopodites of the second maxillae not overreaching those of the first maxillae. Claw of the second maxillae either present or not. Forcipular tergum distinctly wider than long. ...........................................................................................................................3

­ A single, entire clypeal plagula, without a mid­longitudinal areolate stripe. Coxosternum of the first maxillae invariantly divided, with a mid­longitudinal distinct suture. Telopodites of the second maxillae overreaching those of the first maxillae. Claw of the second maxillae invariantly present. Forcipular tergum only slightly wider than long. ......................................................................................................................4

3 Clypeal plagulae not extending to the lateral margins of the clypeus. Coxosternum of the first maxillae undivided, without any mid­longitudinal suture. Genus Arrup ...................................................................8

­ Clypeal plagulae extending along the lateral margins of the clypeus. Coxosternum of the first maxillae divided by a mid­longitudinal suture. Genus Agnostrup . .......................................................... A. paucipes

4 Posterior alae of the labrum with longitudinal stripes and with a marginal fringe. Coxopleura of the last leg­bearing segment with a macropore among smaller, scattered pores. Genus Dicellophilus . ... D. pulcher

­ Posterior alae of the labrum without longitudinal stripes and without a marginal fringe. Coxopleura of the last leg­bearing segment without a macropore distinct from the other pores. Genus Partygarrupius .......... ............................................................................................................................................... P. moiwaensis

5 Invariantly a single, entire clypeal plagula, without a mid­longitudinal areolate stripe. Number of legbearing segments invariantly 45. .................................................................................................................6

­ Invariantly two clypeal plagulae, separated by a mid­longitudinal areolate stripe. Number of leg­bearing segments 45 or more.................................................................................................................................... 7

6 Forcipular tarsungulum with a distinct tooth emerging on the dorsal surface, at about one third of the length ( Fig. 80). Spiculum present. Telopodites of the second maxillae not overreaching those of the first maxillae. Genus Takashimaia . ................................................................................................. T. ramungula

­ Forcipular tarsungulum without a tooth emerging on the dorsal surface ( Fig. 84). Spiculum absent. Telopodites of the second maxillae overreaching those of the first maxillae. Genus Tygarrup .................... ........................................................................................................................................... T. takarazimensis

7 Clypeal plagulae extending along the lateral margins of the clypeus (e.g. Figs. 46, 49, 50). Spiculum usually present. Posterior margin of the labral side­pieces without a distinct series of notches, other than 1–2 close to the medial end. Telopodites of the second maxillae overreaching those of the first maxillae (e.g. Figs. 64, 69). Only 1–2 tiny spines on the tip of the legs of the last pair. Genus Mecistocephalus .......... 16

­ Clypeal plagulae not extending to the lateral margins of the clypeus (e.g. Fig. 74). Spiculum invariantly absent. Posterior margin of the labral side­pieces with a distinct series of notches. Telopodites of the second maxillae not overreaching those of the first maxillae (e.g. Fig. 75). A tubercle bearing more than 2 tiny spines on the tip of the legs of the last pair. Genus Proterotaiwanella . .............................................33

8 Claw of the second maxillae present, clearly recognisable ( Fig. 12). Forcipular article III with a well developed tooth ( Fig. 13). Poison calyx reaching the distal part of the forcipular article I in both sexes. ... ..................................................................................................................................................... A. dentatus ­ Claw of the second maxillae absent. Forcipular article III without a developed tooth, usually with only a tiny tubercle (e.g. Figs. 5, 17, 21, 25). Poison calyx variously elongated inside the forcipular segment, sometimes sexually dimorphic in elongation. ............................................................................................9

9 Body length reaching at least 5 cm. Forcipular tarsungulum apparently without any basal tubercle or tooth ( Fig. 8). Forcipular article III without any tubercle. Sternum of the last leg­bearing segment evidently longer than wide. .......................................................................................................................... A. sauteri

­ Body length usually not reaching 5 cm. Forcipular tarsungulum with a basal tubercle or tooth (e.g. Figs. 5, 13, 17, 29). Forcipular article III usually with a tiny tubercle. Sternum of the last leg­bearing segment wider than long or as wide as long. ...........................................................................................................10

10 Body length of adults about 1 cm. Frontal line not evident. Basal article of the telopodite of the second maxillae bearing an evident spiniform projection at the distal­external end. Distal tooth of the forcipular article I very long and thin ( Fig. 25). ..................................................................................... A. lilliputianus

­ Body length of adults at least 2 cm. Frontal line evident. Basal article of the telopodite of the second maxillae without any evident spiniform projection at the distal­external end. Distal tooth of the forcipular article I usually not very long and thin. .......................................................................................................... 11

11 Basal part of the medial projections of the first maxillae about 3 times as long as the distal lobe, with evidently swollen internal margin ( Fig. 9). Distal article of the telopodite of the second maxillae apparently more than 3 times as long as wide. ............................................................................................ A. areolatus

­ Basal part of the medial projections of the first maxillae less than 3 times as long as the distal lobe, the internal margin not particularly swollen (e.g. Fig. 4, 16, 20, 28). Distal article of the telopodite of the second maxillae less than 3 times as long as wide. ........................................................................................12

12 Body length reaching about 5 cm. Distal tooth of the forcipular article I rounded, not evidently tapering ( Fig. 17). Poison calyx of males reaching the base of the forcipular article I. ........................... A. ishiianus

­ Body length not reaching 4 cm. Distal tooth of the forcipular article I pointed, evidently tapering (e.g. Fig. 5, 7, 21). Poison calyx of males often reaching the posterior part of the forcipular coxosternum. ..........13

13 Basal tooth of the forcipular tarsungulum shallow and obtuse (e.g. Fig. 29)............................................ 14

­ Basal tooth of the forcipular tarsungulum projecting and sharp ( Figs. 5, 21). .......................................... 15

14 Each coxopleuron of the last leg­bearing segment with ca. 40 pores in specimens about 2 cm long. Medial projections of the first maxillae unknown. ................................................................................... A. obtusus

­ Each coxopleuron of the last leg­bearing segment with ca. 15 pores in specimens about 2 cm long. Medial projections of the first maxillae very elongated, their distal lobe about 3.5 times as long as wide. ............. .................................................................................................................................................. A. longicalix

15 Basal tooth of the forcipular tarsungulum sharp, quite small and projecting forward. .................. A. holstii

­ Basal tooth of the forcipular tarsungulum triangular, large and projecting inward. ............. A. kyushuensis

16 Number of leg­bearing segments higher than 50. Trunk invariantly without dark patches. Plagulae invariantly with pore­like sensilla (e.g. Fig. 50). Buccae without setae. ............................................................17

­ Number of leg­bearing segments either 45 or 49. Trunk with or without dark patches. Plagulae with or without pore­like sensilla. Buccae with setae............................................................................................ 18

17 Number of leg­bearing segments 57 or 59. Body length not overreaching 6 cm. Clypeus less than 1.9 times wider than long. Clypeal ratio less than 1.6. Number of clypeal setae less than 10. .......................... ........................................................................................................................................... M. diversisternus

­ Number of leg­bearing segments 63 or 65. Body length overreaching 6 cm. Clypeus more than 1.9 times as wide as long. Clypeal ratio more than 1.6. Number of clypeal setae more than 20. ............ M. japonicus

18 Number of leg­bearing segments invariantly 45. Head about 1.4–1.5 times as long as wide. Sternal sulcus not furcate. .................................................................................................................................................19

­ Number of leg­bearing segments invariantly 49. Head usually more than 1.4 times as long as wide. Sternal sulcus either furcate or not......................................................................................................................... 21

19 Clypeal ratio about 1.0. Forcipular article I with two teeth, similar in size ( Fig. 41). ..... M. momotoriensis

­ Clypeal ratio more than 1.5. Forcipular article I with only one, distal tooth.............................................20

20 Clypeal plagulae more than 3 times as wide as long. Posterior ala of the labrum subrectangular, the external margin as long as the internal margin ( Fig. 43). ............................................................... M. satumensis

­ Clypeal plagulae less than 2.5 as wide as long. Posterior ala of the labrum subtriangular, the external margin reduced to a vertex ( Fig. 37). .......................................................................................... M. nannocornis

21 Areolate part of the clypeus with smooth insulae (e.g. Figs. 46, 49, 50). Plagulae with or without pore­like sensilla. Anterior ala of the labrum subrectangular, the internal margin not reduced to a vertex. ............22

­ Areolate part of the clypeus without smooth insulae (e.g. Figs. 51–53). Plagulae invariantly without porelike sensilla. Internal margin of the anterior ala of the labrum either reduced to a vertex or not..............26

22 Head about 1.5 times as long as wide. Plagulae invariantly without pore­like sensilla. Anterior half of the buccae bearing a group of setae ( Fig. 49). .................................................................................... M. mikado

­ Head more than 1.6 times as long as wide. Plagulae with or without pore­like sensilla. Anterior half of the buccae without setae. .................................................................................................................................23

23 Several, dense pore­like sensilla on the antero­external part of the plagulae and on the anterior half of the buccae ( Fig. 50). Sternal sulcus not furcate. ......................................................................... M. marmoratus

­ Plagulae and buccae without pore­like sensilla, at most with about 3 spine­like sensilla on the anteroexternal part of each plagula ( Figs. 46, 54). Sternal sulcus either furcate or not. .....................................24

24 Clypeal ratio less than 1. Basal tooth of the mandible much shorter than the first lamella, its margin sawlike ( Fig. 55). An intermediate lamella of the mandible with about 30–40 teeth. Sternal sulcus furcate. .... ............................................................................................................................................ M. multidentatus

­ Clypeal ratio about 1 or more. Basal tooth of the mandible reaching the tip of the first lamella, its margin entire ( Figs. 47, 68). An intermediate lamella of the mandible with less than 30 teeth. Sternal sulcus not furcate. .......................................................................................................................................................25

25 Trunk usually with dark patches in adults. Clypeus of fully­grown specimens with 4–6 insulae per side. Distal tooth of article I of the forcipules evidently larger than the basal tooth ( Fig. 70). ....... M. karasawai

­ Trunk without dark patches in adults. Clypeus of fully­grown specimens with 3–4 insulae per side. Distal and basal teeth of article I of the forcipules similar in size ( Fig. 48). ...................................... M. rubriceps

26 Clypeus with about 3–4 setae on each side. Sternal sulcus furcate or not.................................................27

­ Clypeus with more than 8 setae on each side (e.g. Fig. 52). Sternal sulcus furcate. ................................31

27 Clypeal ratio about 3.0. Medial projections of the first maxillae about 6 times as long as wide, overreaching the frontal margin of the head ( Fig. 58). ........................................................................ M. longichilatus

­ Clypeal ratio less than 3.0. Medial projections of the first maxillae no more than 3 times as long as wide, not overreaching the frontal margin of the head (e.g. Fig. 64) ..................................................................28

28 Clypeal ratio more than 2 ( Fig. 62). .............................................................................................. M. changi

­ Clypeal ratio less than 1.5 (e.g. Figs. 51, 56). ........................................................................................... 29

29 Trunk with dark patches. Head about 1.8 times as long as wide. Clypeal ratio about 1.4 ( Fig. 51). ............ ............................................................................................................................................. M. monticolens

­ Trunk without dark patches. Head less than 1.7 times as long as wide. Clypeal ratio about 1.0 (e.g. Fig. 56). .............................................................................................................................................................30

30 Head about 1.4 times as long as wide. Mandible: basal tooth about as long as the first lamella, first lamella with about 5 teeth ( Fig. 59). Sternal sulcus not furcate. About 5–6 pores on each coxopleuron in 25 mm long specimens. ...................................................................................................................... M. pauroporus

­ Head about 1.6 times as long as wide. Mandible: basal tooth much shorter than the first lamella, first lamella with about 10 teeth ( Fig. 60). Sternal sulcus furcate. About 30 pores on each coxopleuron in 25 mm long specimens. .............................................................................................................. M. yamashinai

31 Head about 2 times as long as wide. Clypeal ratio about 1.2 ( Fig. 57). Spiculum apparently absent. Basal tooth of the article I of the forcipules apparently absent or reduced to a tubercle. .............. M. yanagiharai

­ Head 1.5–1.7 times as long as wide. Clypeal ratio 2–3 ( Figs. 52–53). Spiculum well developed. Basal tooth of the article I of the forcipules well developed, similar in size to the distal tooth..........................32

32 Head about 1.5 times as long as wide. Sternum of the last leg­bearing segment about twice as wide as long. .................................................................................................................................... M. brevisternalis

­ Head about 1.7 times as long as wide. Sternum of the last leg­bearing segment about as long as wide....... .......................................................................................................................................................... M. ongi

33 Number of leg­bearing segments 49. Clypeal ratio about 4. .................................................... P. sculptulata

­ Number of leg­bearing segments 45. Clypeal ratio about 3. ........................................................ P. tanabei