Arrup longicalix, Published, 2007

Published, First, 2007, The Mecistocephalidae of the Japanese and Taiwanese islands (Chilopoda: Geophilomorpha), Zootaxa 1396, pp. 1-84 : 23-24

Arrup longicalix n. sp.

Figs. 26–29

Diagnosis. An Arrup species with body length reaching about 2 cm. Frontal line rounded. Distal article of the telopodite of the second maxillae without claw. Medial projections of the first maxillae very elongated, their distal lobe about 3.5 times as long as wide. Tooth of the forcipular tarsungulum very shallow and obtuse. Poison calyx almost reaching the posterior end of the forcipular coxosternum in males. Sternum of the last leg­bearing segment slightly wider than long.

Type material. Holotype: male, 18 mm long, subadult.

Type locality. Mt. Yuwan­dake , Oshima­gun, Amamioshima Id., Kagoshima Pref., Ryukyu Ids, Japan .

Depository of type material. National Science Museum , Tokyo .

Material examined. 1 specimen: male, subadult (18 mm), from Mt. Yuwan­dake , Oshima­gun, Amamioshima Id., Ryukyu Ids, 6.XII.1985, Y. Takai leg., coll. NSMT (holotype) .

Description of the holotype. Male, subadult, body length 18 mm (apical sensilla and most of the antennal setae broken or detached; both telopodites of the last leg­bearing segment lacking). Body colour yellow, without dark patches. Head 1.6 times as long as wide; frontal line curved. Antennae 3.3 times as long as the head width. 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 4.7. Labrum: anterior ala triangular, medial margin reduced to a vertex; internal margins of the side­pieces convergent posteriorly, not touching each other; posterior margin of each side­piece uniformly concave. First maxillae: anterior corners of coxosternum not projecting; medial projections asymmetrical: right projection about 2.7 times as long as wide, internal margin with a few spines, distal lobe about 3.5 times as long as wide, aligned to the external margin of the projection, hyaline scales on the dorsal side present; left projection about 2.3 times as long as wide, distal lobe about 2.0 times as long as wide, spines and scales absent (see Remarks); telopodites symmetrical, each of them about 3.3 times as long as wide, their distal lobes attenuated. Second maxillae: article I of telopodite about 1.9 times as long as wide; article III about 2.6 times as long as wide, with 4 setae at the tip on the internal side; apical claw absent, replaced by small tubercles. Forcipular segment: width to length ratio of exposed part of coxosternum about 1.1; cerrus absent; dorsal ridge of pleuron not developed, but marked by the areolation; scapular point not reaching the anterior margin of the coxosternum. Forcipules: article I about 1.7 times as long as wide, distal tooth pointed and medium­sized (in respect to the other species of Arrup ); article II almost untoothed; article III with a small tubercle; tarsungulum with one basal, low and obtuse tooth; poison calyx not visible, as the poison gland is opaque; poison gland reaching the posterior end of the forcipular coxosternum. A total of 41 leg­bearing segments. Last leg­bearing segment: sternum subtriangular, about 1.1 times as wide as long; about 15 pores on each coxopleuron.

Distribution in the considered area.

Ryukyu Islands : Mt. Yuwan­dake, Amamioshima Id. (type locality) .

General distribution. Only known from the type locality.

Derivatio nominis. The name refers to the unusual size of the poison apparatus in the only known male.

Remarks. The asymmetric condition of the two medial projections of the first maxillae ( Fig. 29) could be due to a teratological state of the left projection, which is smaller than the right one and lacks any spine and hyaline scale, whereas the right projection could represent the normal condition, as it is provided with spines and hyaline scales, which are regularly present in Arrup and other Mecistocephalidae .

However, we cannot rule out the possibility of something like a compensatory growth, one projection being overgrown to the detriment of the other. Even in this case, a putative intermediate projection between the two described ones would be diagnostic for this species, as unusually slender in respect to all other Arrup species.

In this species the actual length of the calyx is unknown, as the gland remained opaque even after long treatment with lactophenol and we preferred not to digest the only available specimen with proteolitic substances. Even though an extension of the poison gland well beyond a short calyx is known in some geophilomorphs (for example in some Ballophilidae and Schendylidae ; see Crabill, 1960), it seems reasonable to hypothesize that in Arrup longicalix the morphometric relationship between the calyx and the gland is the same as in other related species and therefore the calyx extends to almost the posterior end of the forcipular coxosternum.