Eoseviulisoma Brolemann, 1920

Enghoff, Henrik, 2018, A mountain of millipedes VII: The genus Eviulisoma Silvestri, 1910, in the Udzungwa Mountains, Tanzania, and related species from other Eastern Arc Mountains. With notes on Eoseviulisoma Brolemann, 1920, and Suohelisoma Hoffman, 1963 (Diplopoda, Polydesmida, Paradoxosomatidae), European Journal of Taxonomy 445, pp. 1-90 : 79-81

The status of Eoseviulisoma Brolemann, 1920

Eoseviulisoma was proposed as a subgenus of Eviulisoma by Brolemann (1920) on the basis of the following characters:

- No process between the 4th male legs (vs a process present in Eviulisoma s. str.)

- Male sternum 6 with a very shallow excavation (vs a pronounced excavation in Eviulisoma s. str.)

- Gonopodal prefemur (“tronc du télopodite”) longer than the distal processes (“les rameaux”) (vs shorter in Eviulisoma s. str.)

- Transverse suture of body rings striolate (“perlée”) (vs smooth in Eviulisoma s. str.)

The type and only species of Eoseviulisoma was Strongylosoma julinum Attems, 1909 .

Hoffman (1953) elevated Eoseviulisoma to a full genus and transferred Dyseviulisoma abnorme Attems, 1937 to it. In his key to African eviulisomatinine genera, Hoffman separated Eoseviulisoma from Eviulisoma in the first couplet in which genera with a large mesapical lobe on the gonopod coxa ( Eviulisoma and Suohelisoma ) were separated from genera without such a lobe ( Scolodesmus, Eoseviulisoma and Wubidesmus ) ( Hoffman 1971). A third species, Eviulisoma (Eoseviulisoma) rugegianum Attems, 1953 , was regarded as “generic status uncertain” by Jeekel (1968), but judging from the original description it may be included in the present rather broad concept of Eviulisoma .

VandenSpiegel & Golovatch (2014) pointed out some difficulties in distinguishing these two genera. Thus, Eviulisoma ngaia VandenSpiegel & Golovatch, 2014 , has a process between the 4th male legs, but no excavation on sternum 6. Eviulisoma taitaorum VandenSpiegel & Golovatch, 2014 , has no process between the 4th male legs, but is does have an excavated sternum 6 and a smooth suture. They therefore argued that the two genera “may well prove to be synonymous”.

The Udzungwan species studied here offer further examples in favour of this suggestion. Thus, E. biquintum sp. nov. has two processes on sternum 5, one between the 4th legs and one between the 5th, but no excavation on sternum 6. Striolation of the transverse suture seems to be quite variable: in some Udzungwan species the suture is clearly striolate ( Fig. 5 A ), in others the striolation is indistinct, and in still others the suture is virtually smooth. The relative length of the prefemur and acropodite is also variable; however, most species have the prefemur less than half the length of the acropodite.

Existing illustrations of the gonopod of E. julinum ( Attems 1909; Brolemann 1920) are not very clear concerning the acropodital part. Thanks to Sara B. Frederiksen, I have been able to examine a male of E. julinum from Tanzania, Kilimanjaro Region, Moshi Vijijini (rural) District, Mt Kilimanjaro, lower montane forest plot 4, 1623 m a.s.l., 03°15′27.79″ S, 37°25′12.74″ E, 9 Apr. 2014, S. Frederiksen leg. and det. (ZMUC). Figure 38 shows several images of the right gonopod of the specimen. There is a relatively pronounced ʻ Eviulisoma typeʼ coxal lobe (contra Hoffman 1971; the lobe is also evident in Brolemann 1920: figs 85–86). The prefemoral part is long – as long as or even longer than the acropodital part. The acropodite consists – in addition to the flagelloid solenomere – of a relatively short, simple, lamelloid mesal acropodital process (map) and a large complicated solenophore which is split at ca half its length into a mesal process with a rounded, finger-shaped tip and a triangular expansion ca at mid-length, and a large lateral lamella which is rolled up to form a conductor for the solenomere. The entire gonopod telopodite is quite short and does not reach the unexcavated sternum 6.

The second species referred to Eoseviulisoma by Hoffman (1953), E. abnorme , does indeed, according to the original illustrations of Attems (1937), have the gonopod telopodite reminiscent of that in E. julinum , but according to Attems, the 6th sternum is excavated. The same applies, more or less, to E. rugegeanum .

In conclusion, considering the wide variability in acropodite structure seen in ʻtypicalʼ species of Eviulisoma , there is no justification for recognizing Eoseviulisoma as a separate taxon at the generic or subgeneric level. The suggestion by VandenSpiegel & Golovatch (2014) is endorsed, and Eoseviulisoma is herewith synonymized under Eviulisoma . Of course, the name will remain available if at some point it becomes desirable to recognize subgenera in Eviulisoma .

Figures

Fig. 5. Eviulisoma paradisiacum sp. nov., ♂. A. Two midbody rings, lateral view, showing pleurosternal keel and striolate stricture. B. Two midbody rings, ventral view, showing sternal cones. C–E. Telson. C. Ventral view. D. Dorsal view. E. Posterior view. Abbreviations: ep = epiproct; hy = hypoproct; lt = lateral tubercle; oZ = ozopore; pk = pleural keel; pp = paraproct; sc = sternal cone; sp = spinneret; str = stricture; tt = terminal tubercle. Scale bars: 0.1 mm.

Fig. 38. Eviulisoma julinum (Attems, 1909), specimen from Mt Kilimanjaro, S. Frederiksen leg., right gonopod. A. Lateral view. B. Mesal view. C. Anteroventral view. D. Dorsal view. Abbreviations: cxl= coxal lobe; map = mesal acropodital process; slm = solenomere; sph = solenophore. Scale bars: A–B = 0.1 mm; C–D = 0.05 mm.