Key to Udzungwan s. str. species of Eviulisoma

The key is based on adult males. Identifications should always be checked against the species descriptions and illustrations, as additional species of Eviulisoma are expected to exist in the Udzungwa Mts.

1. Sternum 6 with a deep excavation...................................................................................................2

– Sternum 6 not excavated................................................................................................................21

2. Gonopod with an intermediate acropodital process (iap)................................................................3

– Gonopod without an intermediate acropodital process..................................................................15

3. Acropodite with a finger-shaped basal process (Fig. 9: bap) ........... E. kwabuniense Kraus, 1958

– Acropodite without a basal process.................................................................................................4

4. Dorsal lobe of solenophore (sph -d) in the shape of a very large hook (Fig. 13) ..... E. cetafi sp. nov.

– Dorsal lobe of solenophore different.................................................................................................5

5. A strong hook emerging from concave side of solenophore (Fig. 21: sph-h) ................................. ..................................................................................................................... E. paradisiacum sp. nov.

– No strong hook emerging from concave side of solenophore..........................................................6

6. Large species (width 2.6–3.3 mm) with contrasting dark and pale transverse bands; dorsal lobe of two-lobed solenophore (sph-d) large, as long as acropodital processes and ending in a hook (Figs 8 A, 12) ....................................................................................................... E. akkariae sp. nov.

– Smaller species (width 1.5–2.1 mm), (always?) without contrasting transverse bands; solenophore different..............................................................................................................................................7

7. Gonopods with four very to extremely slender processes (Fig. 19: iap, map, sph-d, sph-v) ......... ........................................................................................................................... E. nessiteras sp. nov.

– At least some of these processes stouter .........................................................................................8

8. Intermediate acropodital process (iap) much shorter than mesal acropodital process (map); dorsal lobe of solenophore (sph-d) bifid (Fig. 17) .................................. E. kalimbasiense sp. nov.

– Intermediate acropodital process as long or almost as long as mesal acropodital process; dorsal lobe of solenophore different...........................................................................................................9

9. Mesal acropodital process (map) with a long, curved side branch fitting over semicircular dorsal lobe of solenophore (sph-d) (Fig. 18) ................................................ E. navuncus sp. nov.

– Mesal acropodital process different............................................................................................10

10. Solenophore with three elongate lobes...........................................................................................11

– Solenophore with two lobes, sometimes with a rudimentary intermediate lobe as well............14

11. All three lobes of solenophore of equal length, but intermediate lobe (sph-i) thinner than the others (Fig. 11) ........................................................................................... E. aequilobatum sp. nov.

– The three lobes of solenophore of unequal length........................................................................12

12. Intermediate lobe of solenophore (sph-i) much shorter than the slender, approximately equally long dorsal and ventral lobes (sph-d and sph-v) (Fig. 15) ............................. E. commelina sp. nov.

– Dorsal lobe of solenophore (sph-d) much longer than intermediate and ventral lobes (sph-i and sph-v) ...............................................................................................................................................13

13. Intermediate and ventral lobes of solenophore (sph-i and sph-v) slender; subapical side branch of mesal acropodital process (map) directed laterad (Fig. 14) ....................... E. chitense sp. nov.

– Intermediate and ventral lobes of solenophore (sph-i and sph-v) very short and broad; subapical side branch of mesal acropodital process (map) directed obliquely apicad (Fig. 20) ....................... ........................................................................................................................... E. ottokrausi sp. nov.

14. Solenophore with two broad lobes; mesal acropodital process (map) ending in two subequal points (Fig. 10) .................................................................................................... E. acaciae sp. nov.

– Solenophore with a stout dorsal lobe (sph-d), a slender ventral lobe (sph-v) and a rudimentary intermediate lobe (sph-i); mesal acropodital lobe (map) ending in a hooked point and with a small, pointed subapical side branch (Fig. 16) .......................................................... E. ejti sp. nov.

15. Sternum 6 excavation with four-lobed or angled rim (Figs 26 A, 30 A, 34F).................................16 – Sternum 6 excavation with a simple rim (as Fig. 6 A –C)...............................................................18

16. Sternum 6 excavation with angled rim (Fig. 34F); mesal acropodital process (map) with large subapical hook opposing corresponding hook on solenophore (Fig. 34 A –B, D) ............................ .......................................................................................................................... E. angulatum sp. nov.

– Sternum 6 excavation with four-lobed rim (Figs 26 A, 30 A); gonopods different....................17

17. Smaller species (width 2.0 mm); a dentate ridge present on mesal acropodital process (map) (Fig. 27) ............................................................................................................. E. sternale sp. nov.

– Larger species (width 3.0– 3.2 mm); no dentate ridge on map (Fig. 31) .............. E. zebra sp. nov.

18. Gonopod acropodite with a separate basal ʻfemoriteʼ; solenophore large, plate-like (Fig. 33) .... ....................................................................................................................... E. articulatum sp. nov.

– No separate ʻfemoriteʼ; solenophore slender, tube-like (ʻrolled sheetʼ).......................................19

19 Larger species (width 2.5–3.4 mm); ventral margin of mesal acropodital process (map) strongly convex (Fig. 25) ........................................................................................ E. grumslingslak sp. nov.

– Smaller species (width 1.8–2.4 mm); ventral margin of map almost straight..........................20

20. Gonopod coxa with a slender distolateral process (Fig. 23 A: cxp) ............... E. coxale sp. nov.

– Gonopod coxa without a distolateral process (Fig. 22) ..................... E. dabagaense Kraus, 1958

21. Sterna 5 and 6 each with a knob-like process (Fig. 35) ................................ E. biquintum sp. nov.

– Sterna 5 and 6 without processes (Fig. 36) ................................................. E. breviscutum sp. nov.

Distribution and habitat patterns

All Udzungwan s. str. species of Eviulisoma are endemic to the Udzungwa Mts. Figure 37 shows the distribution of the 22 species plotted on a diagrammatic map of the areas within the Udzungwas where the species have been collected. Only three species ( E. dabagaense, E. navuncus sp. nov. and E. nessiteras sp. nov.) have been found in more than one area. The Udzungwa Mts National Park, where the highest number of species (nine) has been found, shares no species with other areas.

Table 4 shows the altitudinal distribution of the Udzungwan s. str. species. Although some species occur as low as 800 m a.s.l., the highest diversity occurs from 1400 m a.s.l. upward. Eviulisoma covers a larger altitudinal spectrum than the Chaleponcus dabagaensis group, which is restricted to 1500–2200 m a.s.l. with a maximum at 1800–2000 m a.s.l. (Enghoff 2014, 2017).

Habitat information is included on the labels of many specimens, and a small amount of habitat information can be extracted from the literature (Kraus 1958, Frontier Tanzania 2001). In by far the most cases, the habitat is indicated as forest, montane rain forest, tropical semi-evergreen forest, etc. Some species have been collected in open Acacia woodland ( E. acaciae sp. nov., E. grumslingslak sp. nov.) or ʻscrub / thicket/ bushʼ ( E. ottokrausi sp. nov.), but the two last-mentioned have also been collected in proper forests.