Strongylosomides Attems, 1901

Golovatch, Sergei I., Bouzan, Rodrigo S., Gallo, Jéssica S. & Bichuette, Maria E., 2022, A new genus and two new species of the millipede family Chelodesmidae from Bahia state, northeastern Brazil, including a likely troglobiont (Diplopoda, Polydesmida), Zootaxa 5155 (1), pp. 87-104 : 91

Genus Strongylosomides Attems, 1901

Type species: Leptodesmus petropolites Attems, 1901 , by monotypy.

Species included:

Strongylosomides azevedoi (Schubart, 1945) , São Paulo state;

Strongylosomides cognatus (Brölemann, 1902) , São Paulo state;

Strongylosomides cylindricus (Brölemann, 1902) , São Paulo state;

Strongylosomides maritimus (Schubart, 1951) , Rio de Janeiro state;

Strongylosomides nuptae (Schubart, 1955) , São Paulo state;

Strongylosomides petropolites (Attems, 1901) , Rio de Janeiro state;

Strongylosomides soaresi (Schubart, 1946) , Rio de Janeiro state;

Strongylosomides stercoriarius Schubart, 1956 , comb. nov. ex Leptodesmus de Saussure, 1859 , from Minas Gerais state;

Strongylosomides troglobius sp. nov., Bahia state, and

Strongylosomides virgulatus (Attems, 1901) , Rio de Janeiro state.

Hoffman’s (1979) revision provides diagnoses for most species, but no key is presented.

Diagnosis. A genus of Chelodesmidae unique in showing small, low and smooth paraterga, a smooth and distinctly convex dorsum, small pleurosternal carinae, unmodified postgonopodal sterna, relatively short legs sometimes equipped with distoventral chelae/bulges on male tibiae, combined with gonopods of moderate size, robust, set in a simple ovoid aperture, and devoid of a central sternal rudiment; gonocoxae (Cx) abut along a long sinuous line of contact, each gonocoxa supplied with an unmodified cannula (c) devoid of adjacent setae subtending it on the mesal side, but often with a small to moderate distodorsal apophysis; gonopodal telopodites (Te) rather stout and robust, set subrectangular to Cx, directed anteriorly and showing a medium-sized prefemoral region (= densely setose part, Pf) clearly set off from acropodite by oblique sulci (= cingulum) on both mesal and lateral sides, with a welldeveloped, usually suberect, often distad enlarged and fully separated prefemoral process (PfP) closely adjacent dorsocaudally to a rather simple and untwisted acropodite (A), PfP only exceptionally and rather obscurely fused basally to A, but distally attenuate, sharp and directed caudally ( Fig. 3 ). Seminal groove (Sg) running entirely on mesal side of Te, ending up on a short solenomere (sl) opposite a similarly short end branch termed the acropodital process (AP) ( Figs 3 , 6 & 7 ).

Remarks. This relatively species-poor genus endemic to Brazil presently comprises only ten, mostly epigean and dark (clearly pigmented) species ranging from the São Paulo state to Bahia along the eastern, Atlantic coast of the country. Hoffman (1979) very finely revised Strongylosomides and even outlined a few species groups. The above refined generic diagnosis largely relies on that paper.

The discovery of a new species to be treated below, the first likely cave-dwelling congener and the first to be recorded from Bahia, not only significantly extends the known distribution area of Strongylosomides to the northeast, but it also allows us to reconsider the status of another old species, Leptodesmus stercoriarius Schubart, 1956 , that has remained lumped so far amongst the still numerous chelodesmids left “orphaned” and ungrouped in limbo within the previously all-embracing genus Leptodesmus de Saussure, 1859 (see Hoffman 1971 and below).

Figures

FIGURE 3. Strongylosomides petropolites (Attems, 1901), male lectotype. A. Left gonopodal telopodite, mesal view (after Hoffman 1979), and Strongylosomides stercoriarius (Schubart, 1956), comb. nov., male syntype. B & C. Right gonopod and its tip, mesal and sublateral views, respectively (after Schubart 1956). Abbreviations: A, acropodite; AP, acropodital process; c, cannula; Cx, gonocoxa; Pf, prefemoral region; PfP, prefemoral process; Sg, seminal groove; sl, solenomere; T, telopodite. Scale bar: 0.1 mm (B) or drawn not to scale (A, C).

FIGURE 6. Strongylosomides troglobius sp. nov., male paratype. A-F. Right gonopod, submesal, mesal, ventral, dorsal, sublateral and lateral views, respectively. Abbreviations: A, acropodite; AP, acropodital process; c, cannula; Cx, gonocoxa; Pf, prefemoral region; PfP, prefemoral process; Sg, seminal groove; sl, solenomere; Te, telopodite. Photographs by K.V. Makarov, taken not to scale.

FIGURE 7. Strongylosomides troglobius sp. nov., male paratype. A-D. Right gonopod with prefemoral process (labeled PfP) highlighted and outlined in red, submesal, mesal, ventral and dorsal views, respectively. Photographs by K.V. Makarov, taken not to scale.