Arrup kyushuensis, Published, 2007

Published, First, 2007, The Mecistocephalidae of the Japanese and Taiwanese islands (Chilopoda: Geophilomorpha), Zootaxa 1396, pp. 1-84 : 19-21

Arrup kyushuensis n. sp.

Figs. 18–21

Diagnosis. An Arrup species with body length of adults ranging between about 1.5 and 3 cm. Frontal line rounded. Distal article of the telopodite of the second maxillae without claw. Tooth of the forcipular article I triangular, large; tooth of the tarsungulum sharp and well developed. Poison calyx almost reaching the posterior end of the forcipular coxosternum in males (but see Remarks), only reaching the distal part of the forcipular article I in females. Sternum of the last leg­bearing segment as wide as long.

Type material. Holotype: male, 28 mm long, adult. Paratype: female, 26 mm long, subadult.

Type locality. Unzen , Shimabara­shi, Nagasaki Pref., Kyushu, Japan .

Depository of type material. National Science Museum , Tokyo, (holotype) .

Material examined. 23 specimens. Type series: 1 male, adult (28 mm), and 1 female, subadult (26 mm), from Unzen, Shimabara­shi, Kyushu , 21.IX.1985, T . Tanabe leg., coll. NSMT and AM (holotype and paratype respectively) . Other specimens: 1 male, subadult (17 mm), 1 female, adult (16 mm), 2 females, subadult (12 and 22 mm), 9 juveniles (9, 11, 13, 13, 13, 14, 14, 15 and 15 mm), same data as holotype, coll. AM and TT ; 3 females, adult (22, 22 and 23 mm), from Mt. Kyogatake, Kashima­shi, Saga Pref., Kyushu , 24.IV.1989, S. Nomura leg., coll. AM and TT ; 1 male, subadult (16 mm), from Nagata­hodo, Yakushima Id., Kagoshima Pref., Ryukyu Ids , 12.VIII.1986, A. Moroto leg., coll. AM ; 2 males, subadult (both 13 mm), and 1 female, subadult (12 mm), from Hanayama­hodo, Yakushima Id., Kumage­gun, Kagoshima Pref., Ryukyu Ids , 18.IX.1985, T . Tanabe leg., coll. TT; 1 male, adult (17 mm), from Shikanosawa, along Hanayama­hodo, Yakushima Id. , Kagoshima Pref., Ryukyu Ids , 11.XI.1985, T . Tanabe leg., coll. AM.

Description of the holotype. Male, adult, body length 28 mm. Body colour yellow, without dark patches. Head 1.4 times as long as wide; frontal line curved. Antennae 3.2 times longer than the head width. Apical sensilla about 8 µm long. Clypeal setae: a median pair anterior to the plagulae and a group on each side of the clypeus, reaching the anterior corners. Clypeal ratio about 2.8. Labrum: internal margins of side­pieces convergent posteriorly, not touching each other; posterior margin of each side­piece slightly sinuous, convex at both ends and concave in the middle. First maxillae: anterior corners of the coxosternum not projecting; medial projection about 2.0 times as long as wide, with seven setae, internal margin with few spines and sinuate near the base, distal lobe about 2.0 times as long as wide, aligned to the external margin of the projection, with parallel margins and only slightly clavate at the tip, and a row of many hyaline scales on the dorsal side; telopodite about 3.1 times as long as wide, curved, with five long setae in the middle, its distal lobe attenuated. Second maxillae: article I of telopodite about 2.1 times as long as wide, the distal­external end bearing a small spine; article III about 2.9 times as long as wide, with about 10 long setae; apical claw absent replaced by 3–4 small tubercles. Forcipular segment: width to length ratio of exposed part of coxosternum about 1.2; cerrus absent; dorsal ridge of pleuron not evident; scapular point not reaching the anterior margin of coxosternum. Forcipules: article I about 1.7 times as long as wide, the distal tooth large, subtriangular, about as long as wide, and clearly projecting outwards; article II smooth; article III with a distinct tubercle; tarsungulum with a well developed basal tooth; poison calyx nearly reaching the posterior end of forcipular coxosternum. A total of 41 leg­bearing segments. Last leg­bearing segment: sternum subtriangular, as wide as long; telopodites with dense and short additional setae on the ventral side and a very small spine at the tip.

Interindividual variation (based on 23 specimens). Total length 17–28 mm. Head 1.4–1.5 times as long as wide. Antennae 2.7–3.2 times as long as the head width. Clypeal ratio 2.4–3.2. Medial projection of the first maxillae 1.7–2.2 times as long as wide, bearing 2–7 setae, basal sinus present or absent. Telopodite 2.6–3.2 times as long as wide, bearing 2–5 long setae in the middle. Second maxillae: article I of telopodite 1.5–2.5 times as long as wide, the distal­external end bearing a small spine or not; article III 1.7–2.7 times as long as wide. Forcipular article I 1.6–2.0 times as long as wide, distal tooth slightly variable in shape and size, but always large and triangular, always projecting. Poison calyx possibly polymorphic in full­grown males (see Remarks), invariably reaching the distal part of the forcipular article I in females and juveniles. Legs of the last pair with dense, short additional setae on ventral side in full­grown males, without additional setae in females and juveniles.

Distribution in the considered area.

Kyushu: Unzen, Shimabara­shi (type locality); Mt. Kyogatake , Kashima­shi .

Ryukyu Islands: Nagata­hodo; Hanayama­hodo; Shikanosawa (all in Yakushima Id.).

General distribution. Kyushu and Yakushima Id.

Derivatio nominis. From Kyushu Id.

Remarks. Males of A. kyushuensis are possibly polymorphic for the size of the poison calyx, as we examined four other males (not mentioned in the material listed above) which agree fully with the diagnosis of this species but for a shorter calyx. In three of these, all subadult (15 and 16 mm long from Nagata­hodo, Yakushima Id., Kagoshima Pref., Japan, 12.VIII.1986, A. Moroto leg., coll. AM and TT; 21 mm long, from Mt. Shiratori­san, Izumi­mura, Yatsushiro­gun, Kumamoto Pref., Japan, 5.IV.1987, S. Nomura leg., coll. AM) the calyx reaches the distal part of the first forcipular article (as in females), whereas in another apparently adult male (16 mm long, from Mt. Shiratori­san, 5.IV.1987, S. Nomura leg., coll. AM) the calyx almost reaches the base of the first forcipular article.

However we cannot rule out the possibility that these males actually belong to a different species, even though the detailed morphological and morphometrical analysis we carried out failed to produce evidence in support of this hypothesis. Indeed, we found preliminary evidence that the calyx length is associated with the presence of additional short setae on the last legs, as three of those four males with shorter calyx have no additional setae or only a few. Further material is needed to assess this hypothesis.

Type specimens are represented by a male with long calyx and a female from the same locality. No males with short calyx were collected at the type locality.

Worth notice is that, in Arrup species , all juveniles examined have a short calyx, suggesting that the calyx elongates with body growth and that the difference between sexes emerges at a later stage.

Also remarkable in this species is the great variability in the relationship between body size and size of gonopods, as we found no trace of gonopods in specimens 9–15 mm long, developing gonopods in specimens 12–26 mm long and fully developed gonopods in specimens 16–28 mm long. But we also found in the same population a 16 mm female with fully developed gonopods and a 22 mm long female with still developing gonopods.