The millipede genus Eviulisoma Silvestri, 1910 in Kenya, with descriptions of new species (Diplopoda, Polydesmida, Paradoxosomatidae)

Abstract The genus Eviulisoma, the largest among Afrotropical Paradoxosomatidae, currently encompasses 36 species or subspecies, including six new from Kenya: Eviulisoma ngaia sp. n., Eviulisoma ngaiaorum sp. n., Eviulisoma taitaorum sp. n., Eviulisoma taita sp. n., Eviulisoma kirimeri sp. n. and Eviulisoma kakamega sp. n. In addition, Eviulisoma alluaudi Brolemann, 1920 and Eviulisoma silvestre (Carl, 1909) are recorded for the first time beyond their type localities in Kenya and Tanzania, respectively, based on new material from Kenya. A key is given to all ten species of the genus presently reported from Kenya.


Introduction
The genus Eviulisoma Silvestri, 1910 is the largest among Afrotropical Paradoxosomatidae, currently known to encompass 30 species or subspecies in central and eastern Africa (Nguyen and Sierwald 2013). The reader is referred to Jeekel (2003) for a most useful review of taxonomic research into Eviulisoma, a detailed new diagnosis, an outline of informal species groups and a key to most of the constituent species.
Tervuren, Belgium (MRAC), a few paratypes have been donated to the Zoological Museum, Moscow State University, Moscow, Russia (ZMUM + entry number). SEM micrographs were taken using a JEOL JSM-6480LV scanning electron microscope. After examination, SEM material was removed from stubs and returned to alcohol, all such samples being kept in MRAC.
Line drawings were very skillfully executed by Mrs Nadine Van Noppen (MRAC). Name. To emphasize the type locality, a noun in apposition. Diagnosis. Differs from all congeners but E. ngaiaorum sp. n. in the absence of a sternal excavation in ♂ segment 6, from E. ngaiaorum sp. n. in the absence of sternal cones in the ♂ and by the presence of a well-developed, phylloid, postfemoral process of the gonopod (Fig. 1C-E). See also Key below.
Gonopods (Fig. 1C-E) compact, with a lamellar solenophore (sph) (= tibiotarsus in Jeekel's (2003) terminology) about as long as a flagelliform solenomere (sl), both being considerably higher than a simple, phylloid, postfemoral process (p). Vulvae densely setose, without peculiarities, as in Fig. 4M Name. To emphasize the type locality, in Latin meaning "a dweller of Ngaia". Diagnosis. Differs from all congeners but E. ngaia sp. n. in the absence of a sternal excavation in ♂ body segment 6, from E. ngaia sp. n. in the presence of sternal cones in the ♂ and only a vestigial gonopod postfemoral process ( Fig. 2C-E). See also Key below.
Sternites behind gonopods with a distinct sharp cone near each ♂ coxa, each caudal pair per diplosegment being a little stronger than anterior one. Setose lobe between ♂ coxae 4 ( Fig. 2C) faintly concave at tip. Sterna between ♂ coxae 6 and 7 (Fig. 2C) clearly flattened, their coxae being a little enlarged and conical distoventrally. Legs densely setose, rather short, 1.2-1.3 times as long as body height (♂), tibiae behind gonopods thereby being mostly subequal in length to tarsi; ♂ tibiae and tarsi with ventral brushes until last two leg-pairs. Gonopods ( Fig. 2C-E) with a lamellar, lateroparabasally strongly expanded solenophore (sph) carrying a large apical claw and two pre-apical teeth, one mesal (m), the other lateral (l); a flagelliform solenomere (sl) about as long as to reach bases of both l and m; postfemoral process (p) very short, fold-shaped, vestigial. Name. To emphasize the type locality, in Latin meaning "a dweller of Taita". Diagnosis. Differs from all congeners in the remarkable size dimorphism, coupled with absence of a sternal lobe between ♂ coxae 4, as well as the subequally long and slender solenophore (sph) and postfemoral process (p) (Figs 3C, 4H-L). See also Key below.
Coloration from pallid, via light pinkish or marbled pinkish brown to nearly chocolate brown, pattern often annulated due to darker metazonae, including later instars of larger morph. Legs pallid to yellowish, earlier instars always entirely pallid. Sometimes a narrow, darker, pigmented axial line and a similar transverse line in caudal 1/3 of metaterga.  frontal edge being densely setose (Fig. 3C). Postgonopodial sterna with small, but evident, sometimes pointed cones near each coxa, anterior pair being always smaller than caudal one on each diplosegment. ♂ tarsi either a little longer than tibiae (usually smaller morph) or both subequal in length (usually larger morph). Legs 1.2-1.4 (♂) or 0.8-0.9 (♀) times as long as body height. ♂ tibiae and tarsi with ventral brushes until last two leg-pairs, their setae being flattened, same as in other new species (Fig. 4D-F).
Vulvae without peculiarities, as in Fig. 4M, N. Remarks. This new species seems remarkable in being represented by two different size morphs which invariably co-occur at least in sufficiently rich samples and show no intermediates. Thus, in one sample from Chawia the adult ♂♂ can vary in size by 1.5-2.0 times. Larger animals tend to be darker than smaller ones.
Such a strong size morphism could be advantageous for the local populations in variably adverse ecological conditions, possibly allowing selection for different life strategies.
The above two species from Taita Hills show parapatry (Map 1), co-occurring only in Fururu Forest.
In addition, the absence of a central lobe between ♂ coxae 4 is rather characteristic of Eoseviulisoma Brolemann, 1920, but the smooth metazonital suture, the structure of the gonopods and the deeply excavate sterna between ♂ coxae 6 and 7 warrant the assignment of this species to Eviulisoma (cf. Brolemann 1920). This is just another example that these two genera may well prove to be synonymous. Both  and   Name. To emphasize the type locality, a noun in apposition. Diagnosis. Differs from congeners by a broadly and regularly rounded hypoproct, coupled with the presence of sternal cones behind ♂ body segment 7, and the lamellar, slender, apically unciform and bidentate solenophore (sph) carrying a lateral tooth midway (t) and reaching about as long as a flagelliform solenomere (sl), both sph and sl being considerably higher than a rather simple, similarly slender, postfemoral process (p). See also Key below.
Coloration from pallid to annulated chocolate brown due to darker metazonae, often with a thin axial pigment line and a similar transverse pigment line in posterior 1/3 of metaterga.
Gonopods (Figs 5C, 6F-J) with a lamellar, slender, apically unciform and bidentate solenophore (sph) carrying a lateral tooth midway (t) and being about as long as a flagelliform solenomere (sl), both sph and sl considerably higher than a rather simple, similarly slender, postfemoral process (p).
Other adult characters as in E. ngaia sp. n., except as follows.

Remarks.
The above is only the second record of this species beyond the type locality: alpine meadows and a forest at 3100 m and 2600 m a.s.l., respectively, on Mt. Kinangop, S00°11', E37°28', Aberdare Ridge, Kenya . Even though the new samples, which are in rather poor condition, fully match Brolemann's (1920) excellent original description, we provide additional illustrations (Fig.  10) to document the identity of this obviously high-montane species which appears to be more widely distributed at least in Kenya (Map 1). The shapes and proportions of the solenophore (sph), solenomere (sl) and postfemoral process (p) are quite characteristic.  Remarks. This is only the second record of this species which has hitherto been known solely from Bakoba, S00°11', E37°28', Tanzania . First described as a variety of E. fossiger , it has since been treated (Hoffman 1953) as a species of full rank, recently very nicely revised and illustrated by Jeekel (2003) from type material. Even though the new samples, which are in rather poor condition, fully match  original description and Jeekel's (2003) redescription, we provide additional illustrations (Fig. 11) to document the identity of this species. The shapes and proportions of the solenophore (sph), solenomere (sl) and postfemoral process (p) which has a conspicuous, parabasal, unciform branch (h) are quite characteristic. E. silvestre appears to be very widely distributed, occurring not only in Tanzania, but also in Kenya (Map 1). Sternal cones absent. Sternal lobe between ♂ coxae 4 large (Fig. 2C). Gonopod postfemoral process (p) large, phylloid, acuminate, but much shorter than a digitiform, suberect, apically rounded, lamellar solenophore (sph) (Fig. 2C-E All ♂ telopodite segments distal to coxa or prefemur with ventral brushes. Epiproct with two distinct apical claws directed ventrad (Fig. 7b). Gonopods divergent, rather loose, with a complex, lamellar, apically unciform (u) solenophore (sph) partly sheathing a longer and flagelliform solenomere (sl); postfemoral process (p) very simple, strong and sickle-shaped ( Fig. 7C-F)  Sternal cones totally absent. Hypoproct acute caudally. Gonopod postfemoral process longest, erect, digitiform, fringed at base on mesal face; both sole-1.5-2.0 times, and is parapatric with a second Eviulisoma species. We are not aware of anything similar among other Paradoxosomatidae, but some Odontopygidae, a purely Afrotropical family of Spirostreptida, also show surprisingly distinct size dimorphism (Didier VandenSpiegel, unpublished results). As noted above, this variability may be advantageous for the local populations in adverse ecological conditions, possibly allowing for selection of different life strategies. Last but not least, even though Eviulisoma is already the largest paradoxosomatid genus in tropical Africa, at the moment counting 36 species or subspecies, there is little doubt that numerous further species will be discovered in the region.