Lithobius (Monotarsobius) meifengensis, a new species of centipede from high altitude forest in central Taiwan (Chilopoda, Lithobiomorpha, Lithobiidae)

Abstract Lithobius (Monotarsobius) meifengensis sp. n. occurring at Mei-Feng Farm, Highland Experimental Farm of National Taiwan University, Nantou, Taiwan, is characterised by a male secondary sexual character on leg 15, a very large ventral swelling occupying almost 50% of the ventral surface of the femur; the gently curved apical region bearing approximately 20 short setae and numerous very small pores of flexo-canal epidermal glands. This male secondary sexual character is described for the first time in the genus Lithobius.


Introduction
In some male Lithobius species, there are secondary sexual characters on the dorsal surface of the femur or tibia of legs 14 and 15 (Lewis, 1981). In Lithobius calcaratus C. L. Koch, 1844, leg 15 has a dorsal wart-like projection on the inner end of the femur (Carballo et al. 1992). For four species described from East Asia: a characteristic crest with long setae as a Chasen-bamboo whisk at the distal end of the tibia of anal legs is present in Lithobius (Monotarsobius) tuberculatus (Murakami, 1965); a small oval region densely covered with small pores of epidermal glands and long setae at the dorsal tibia of legs 15 in Lithobius (Monotarsobius) sasanus (Murakami, 1965); a dorsal wart-like projection is present on the femur of legs 15 in Lithobius (Monotarsobius) dziadoszi Matic, 1970, and a dorsal wart-like projection on the tibia of legs 15 in Lithobius (Monotarsobius) riedeli Matic, 1970. Eason (1973 described the male secondary sexual characters of six species originally assigned to Lithobius, mostly from Central America. a shallow excavation bearing a tuft of setae on the dorsal surface of 14 th tibia, and a small wart-like outgrowth projection from the dorsal excavation on the 15 th tibia in Vulcanbius godmani (Pocock, 1895); a dorsal shallow excavation on the 14 th tibia in Vulcanbius salvini (Pocock, 1895); a crest rises from the dorsal excavation on 15 th tibia in Vulcanbius vulcani (Pocock, 1895); a dorsal wart-like projection on 15 th tibia in both Guerrobius pontifex (Pocock, 1895) and Guerrobius humberti (Pocock, 1895); a dorsal wart-like projection on 15 th femur in Lithobius obscurus (Meinert, 1872).
Antennae with 19 articles ( Figure 2A); basal three articles typically wider than long, following articles markedly longer than wide; distal article much longer than wide, up to 2.8 times as long as wide; abundant setae on antennal surface, less so on basal articles, gradual increase in density to around fourth article, then more or less constant in number.
Six ocelli on each side, one posterior and three dorsal, two ventral, arranged in two irregular row ( Figure 3A); the posterior ocellus comparatively large; ocelli domed, translucent, usually darkly pigmented. Tömösváry's organ comparatively small, nearly rounded; situated at anterolateral margin of cephalic plate, slightly bigger than the adjoining ocelli ( Figure 3B).
Forcipular coxosternite sub-trapezoidal, anterior margin narrow, external side lightly longer than internal side; median longitudinal cleft moderately deep ( Figure 4A); anterior border with 2+2 large triangular coxosternal teeth, inner tooth slightly larger than outer one; porodonts moderately slender, setiform, posterolateral to the outer tooth ( Figure 4B); some scattered setae on the ventral side of coxosternite.
Sternites narrower posteriorly, generally trapeziform, comparatively smooth, setae emerging from pores scattered very sparsely over the surface.
Legs: tarsi fused on legs 1-13 ( Figure 5A), well-defined on legs 14-15; all legs with fairly long claws, curved ventrally; anterior and posterior accessory spines on legs 1-14, the anterior one moderately slender, the posterior spine short and thick (Figure 5B); legs15 lack anterior accessory spines; legs 14-15 with numerous large pores (9.1-11.1 μm) of the telopodal glands on the inner surfaces of femur, tibia, tarsus 1 and tarsus 2 ( Figure 5C), the pores each opening into the centre of a bell-shaped cavity (3.5-3.9 μm) ( Figure 5C), some small pores (1.4-1.6 μm) of flexo-canal epidermal glands sparsely distributed along the border of the epidermal cells ( Figure 5D). Male 15 th legs with secondary sexual character; female legs 15 and other legs without secondary sexual characters on femur or tibia ( Figure 7A). Leg plectrotaxy as in Table 1.  Male secondary sexual character on leg 15: a large domed swelling on the ventral surface of femur, covering almost 50% (Figure 1, 6A); the surface of femoral swelling lacks the large pores of the telopodal glands ( Figure 6B); the gently curved apical region bears approximately 20 short setae, and numerous very small pores (0.8-1.0 μm) of flexo-canal epidermal glands densely distributed ( Figure 6C); a dorsal shallow excavation on the tarsus 2 ( Figure 5C).    Coxal pores: 3333 in males, 3443 or 3444 in females, round, coxal pore field set in a relatively shallow groove, margin of coxal pore-field with slightly eminence.
Male first genital sternite: wider than long, usually well chitinised; posterior margin quite deeply concave between the gonopods, without a medial bulge ( Figure 6D); comparatively long setae evenly scattered on the ventral surface; gonopods short and small, with 2-3 long setae, apically slightly chitinized.
Female sternite 15: generally trapeziform, anterolaterally broader than posterolaterally, posterior margin straight, long setae scattered sparsely over the surface; the sternite of genital segment well chitinised, wider than long; posterior margin of genital sternite deeply concave ( Figure 7B); short to long setae sparsely scattered over the ventral surface of the genital segment.
Female gonopod: first article fairly broad, bearing 11-13 long setae, arranged in three irregular rows; 2+2 sharp coniform spurs, inner spur smaller ( Figure 7A, B); second article with 7-9 rather long setae arranged in two irregular rows on its ventral side; third article usually with 2-3 long setae on its ventral surface; terminal claw undivided, bearing a few thick sensilla coeloconica on its dorsodistal and ventral surface ( Figure 7C).

Remarks
Some Lithobius species, all from Russia, also have distinct sexual characters on male leg 15: the proximal part of male 15 th tibia of Lithobius (Monotarsobius) kurcheavae  Ti  C  t  P  F  Ti  1  ---am  m  --p  ap  a  2  ---am  m  --p  ap  a  3  ---am  m  --p  ap  a  4  ---am  m  --p  ap  a  5  ---am  m  --p  ap  a  6  ---am  m  --p  ap  ap  7 -  (Takakuwa, 1941) [1] Monotarsobius ramulosus Takakuwa, 1941a -Trans. Nat Attems, 1934. However, Takakuwa never came to Taiwan, and never reported these two species in any of his publications. Wang came to Taiwan and studied Taiwanese chilopods since 1953, and he did not record these two species again. We consider that the record of the two species is questionable.