Eviulisoma taitaorum, VandenSpiegel, Didier & Golovatch, Sergei I., 2014

VandenSpiegel, Didier & Golovatch, Sergei I., 2014, The millipede genus Eviulisoma Silvestri, 1910 in Kenya, with descriptions of new species (Diplopoda, Polydesmida, Paradoxosomatidae), ZooKeys 459, pp. 11-34 : 15-17

Taxon classification Animalia Polydesmida Paradoxosomatidae

Eviulisoma taitaorum sp. n. Figs 3, 4, Maps 1, 2

Type material.

Holotype ♂ (MRAC 22630), Kenya, Taita Hills, Chawia Forest, 1500 m a.s.l., S03°29', E38°20', pitfall trapping, 1-20.VI.1999, leg. R. Mwakos.

Paratypes: 3 ♂, 1 ♀, 8 juv. (MRAC 18071), same data, together with holotype; 3 ♂ (MRAC 18016), same locality, 1500 m a.s.l., pitfall traps, 10-26.VI.1999, leg. R. Mwakos; 3 ♀ (MRAC 18096), same locality, 1500 m a.s.l., pitfall traps, III–IV.1999, leg. L. Rogo; 1 ♀, 3 juv. (MRAC 17993), same locality, 1500 m a.s.l., III–IV.1999, leg. D. VandenSpiegel; 3 juv. (MRAC 18505), same locality, Winkler extraction, 7.XII.1999, leg. D. VandenSpiegel & J. P. Michiels; 1 ♂, 2 ♀, 5 juv. (MRAC 18424), same locality, 7.XII.1999, leg. D. VandenSpiegel & J. P. Michiels; 1 ♂ fragment, 1 ♀, 2 juv. (MRAC 18043), 1 ♂, 1 ♀ (ZMUM ρ 2443), Taita Hills, Ngangao Forest, S03°22', E38°21', 1820 m a.s.l., 17.VIII.1999, leg. R. Mwakos; 1 ♂ fragment, 20 ♀ (MRAC 18476), same locality, 4.XII.1999, leg. D. VandenSpiegel & J. P. Michiels; 3 ♀, 3 juv. (MRAC 18008), same locality, 1820 m a.s.l., 19.VI.1999, leg. D. VandenSpiegel; 1 ♀ (MRAC 18090), same locality, 1820 m a.s.l., pitfall traps, III–IV.1999, leg. D. VandenSpiegel, 1 ♂ (MRAC 18036), same locality, 1820 m a.s.l., pitfall traps, 15-17.III.1999, leg. L. Rogo; 1 ♂ (MRAC 22622), Taita Hills, Fururu Forest, S3°26', E38°20', 9.XII.1999, leg. D. VandenSpiegel & J. P. Michiels; 1 ♂, 1 ♀, 7 juv. (MRAC 22623), same locality, pitfall traps, 14-17.XII.2004, leg. A. Bwong, J. Mwandoe & J. Measey; 1 ♂, 1 ♀, 3 juv. (MRAC 18083), Taita Hills, Vuria Forest, S03°24', E38°17', 2200 m a.s.l., 26.VI.1999, leg. D. VandenSpiegel; 1 ♀ (MRAC 18459), Taita Hills, Sagala Forest, S03°50', E38°58', 5.XII. 1999, leg. D. VandenSpiegel & J. P. Michiels.

Non-types: ca 30 juv. (MRAC 18.543), Taita Hills, Fururu Forest, S03°26', E38°20', Winkler extraction, 9.XII.1999; 1 ♀ (MRAC 18441), Taita Hills, Wundanyi, near house, S03°24'07", E38°21'49", 6.XII. 1999, all leg. D. VandenSpiegel & J. P. Michiels.

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, 4 H–L). See also Key below.

Description.

Length of adults ca 17-20 (♂ holotype and some ♂ & ♀ paratypes from Chawia, Fururu and from Ngangao) or 28-38 mm (most of ♂ & ♀ paratypes from Fururu and Ngangao, all few paratypes from Sagala and Vuria), width of midbody metazonae 1.7-1.8 (♂ holotype and some ♂ paratypes) up to 2.0 mm (♀ paratypes from Chawia) or 2.5-2.6 (most of ♂ paratypes from Fururu and Ngangao) up to 3.0-3.8 mm (most of ♀ paratypes from Fururu and Ngangao).

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.

All characters as in Eviulisoma ngaia sp. n. (Fig. 4 A–G, M, N), except as follows.

Surface rather smooth and shining (Figs 3, 4 A–C, H), near ozopores faintly rugulose longitudinally, slightly microgranulate below in ♂. Hypoproct more narrowly rounded up to nearly pointed between 1+1 caudal setae (♂). Pleurosternal carinae faint (Fig. 4H), mostly line-shaped, visible until segment 17 (♂) or 15 (♀). Sterna between ♂ coxae 4 and 5 each with a pair of paramedian cones caudally, devoid of any central lobes (Figs 3C, 4H); sterna between ♂ coxae 6 and 7 unusually deeply excavate and ledge-shaped for accommodation of gonopod tips (Fig. 4H), the excavation’s 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. 4 D–F).

Gonopods (Figs 3C, 4 H–L) very slender, with solenophore (sph), postfemoral process (p) and solenomere (sl) subequal in length.

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 Brolemann (1920) and Attems (1937) had treated Eoseviulisoma as only a subgenus of Eviulisoma , but Hoffman (1953) elevated the former to the rank of a full genus which currently includes only 2-3 species from Tanzania and the Democratic Republic of the Congo.