CHELODESMIDAE Cook, 1895

Bouzan, Rodrigo S., Iniesta, Luiz Felipe M., de Souza, Claudio A. R., Zampaulo, Robson A. & Brescovit, Antonio D., 2020, Taxonomic review of the Amazonian millipede genus Parastenonia Hoffman, 1977 and description of a new species from iron-ore caves (Polydesmida: Chelodesmidae), Journal of Natural History 53 (45 - 46), pp. 2781-2799 : 2782-2784

Family CHELODESMIDAE Cook, 1895

Subfamily CHELODESMINAE Cook, 1895

Tribe Priodesmini Hoffman, 1977

Genus Parastenonia Hoffman, 1977

Parastenonia Hoffman, 1977: 449 – 459 . Type species: Priodesmus aurae Schubart, 1947 [= Priodesmus parae Cook 1895 ], by original designation. Hoffman 1980: 152; Shelley et al. 2000: 120.

Diagnosis

Males of Parastenonia differ from those of other chelodesmid genera by the combination of the following characters: metaterga granular and crossed by a transversal sulcus ( Figure 4 (d)), as in Cypraeogona , Cayenniola , Cearodesmus and Brasiloschubartia , from which however this genus differs in the shape of the gonopod; lateral edge of paranota trilobed by the presence of two deep sinuses ( Figure 4 (a,b)), as in Priodesmus and Stenonia , (see Attems 1938, figs 68 – 69; Jeekel 1963, figs 30 – 32) however without modifications on the walking legs; gonocoxae large, with a dorsal field of setae; a long slender acuminate process on acropodite and an elongated prefemoral process ( Figure 9 (a,b)).

Redescription

General measurements. Body length between 32.30 mm (female of P. parae ) and 22.60 mm (male of P. carajas sp. nov.).

Colouration (in 70% ethanol). Variable among species, ranging from reddish brown to ochre.

Head. With scattered tubercles, some of which bearing setae ( Figure 2 (a – f)); shape of the incisura lateralis suboval. Antenna elongated, about 1.5x the width of midbody ring ( Figure 3 (a – d)).

Body rings. Integument with small tubercles, without setae ( Figure 4 (a,b,d,e)). A transversal groove on the metazonite. Collum with the anterior border arched and posterior border straight. Spiracles oval. Sternites without modifications. Ozopores on trunk rings: 5, 7, 9, 10, 12, 13, 15 – 19 (the standard polydesmid pore formula), located at the tip of the intermediate paranotum; and surrounded by peritremata. Paranota: prominent and long, wide, covering part of the legs, without setae on the edges. Paranota divided laterally into three lobes: -pro; -meso and -meta ( Figure 4 (a,b)). Telson: triangular, wide and with tubercles ( Figure 4 (e)). Epiproct with five pairs of macrosetae projecting through the tubercles on the dorsal side and two pairs in the apical region; paraproct with two macrosetae on each valve; hypoproct with two macrosetae.

Legs. Granulated; scattered setae along the entire surface ( Figure 4 (c)).

Male sexual characters. Gonopore located on the coxae of the legs of the third body ring, coxae rounded, with a large apical pore ( Figure 9 (a)). Gonopod aperture large, rectangular-shaped; posterior edge slightly folded ( Figures 8 (a – b) and 9(b)). Gonopods: coxae (Cx; Figures 6 (a) and 9(c,d)) equivalent to about half the length of the telopodite, without spiniform process, with several setae on dorsal side; coxae dorsally prominent in ectal view. Cannula (C; Figure 9 (e)) robust and hook-shaped. Spermatic groove: runs along the mesal side of the acropodite in the entire length (SG; Figure 6 (b)). Telopodite elongated, divided into two parts: the prefemoral region ( Figure 9 (d)) and the femoral region ( Figure 9 (d)). Prefemoral process ( Figure 9 (d)): branch long with stretch marks ( Figure 9 (f)). Acropodite long divided into two parts, the larger central branch is the solenomere carrying the spermatic groove with a thin elongated branch, rising proximally from the femoral region ( Figure 9 (d)).

Female sexual characters. Cyphopods elongated, situated directly behind the second pair of legs on the third body ring; composed of valves and operculum, all densely setose; two valves joined by a membrane and operculum apically, appressed against both larger

valves ( Figures 6 (c – f) and 10(a – e)). A small projection of the valves with S-shaped curvature in the intermediate membrane ( Figures 6 (c,d) and 10(a)).

Included species

Two species: Parastenonia parae ( Cook, 1895) and P. carajas sp. nov.

Distribution

Known only from Amazon rainforest in the state of Pará, Brazil ( Figure 11 ).

Figures

Figure 2. Parastenonia carajas sp. nov. male (IBSP 4997): (a) Head; (b) SEM of head (incisura lateralis in detail); (c) Labrum; (d) Detail of the occipital region; (e) Tubercles bearing-setae (setae in detail); (f) Small tubercles without setae. Scale bars: (a) 400 µm; (b) 500 µm; (c) 400 µm; (d) 300 µm; (e) 100 µm; (f) 100 µm.

Figure 3. Parastenonia carajas sp. nov. male (IBSP 4997), SEM of the antennae: (a) Antenna; (b) Detail of the fifth antennomere and the basiconic sensilla; (c) Basiconic sensilla in detail; (d) Apical sensory cones. Scale bars: (a) 500 µm; (b) 200 µm; (c) 40 µm; (d) 50 µm.

Figure 4. Parastenonia carajas sp. nov. male (IBSP 4997), SEM of the body rings and legs: (a) Midbody paranota with ozopore; (b) Midbody paranota without ozopore; (c) Midbody leg; (d) Midbody rings; (e) Telson. Scale bars: (a) 400 µm; (b) 400 µm; (c) 500 µm; (d) 1 mm; (e) 400 µm.

Figure 6. Parastenonia parae male (MNRJ 11825) and female (MZUSP 1082), microscope and stereoscope images of the gonopod and cyphopods: (a) Gonopod in mesal view; (b) Distal portion of the gonopod; (c) Cyphopod in ectal view;(d) Detail of the junction between the internal and external valva; (e) Cyphopod in posterior view;(f) Cyphopod in anterior view.Scale bars: (a) 500 µm;(b) 250 µm;(c) 500 µm;(d) 250 µm; (e) 500 µm; (f) 500 µm.

Figure 8. Parastenonia carajas sp. nov. male holotype (IBSP 1914), gonopods: (a) Ventral portion with the gonopod aperture; (b) Gonopod aperture in detail; (c) Gonopod in ectal view; (d) Gonopod in mesal view. Scale bars: (a) 1000 mm; (b) 500 µm; (c) 500 µm; (d) 500 µm.

Figure 9. Parastenonia carajas sp. nov. male (IBSP 4997), SEM of the aperture and of the gonopod: (a) Apical pore; (b) Gonopod aperture in detail; (c) Gonopod in ectal view; (d) onopod in mesal view; (e) Cannula; (f) Tip of the acropodite in detail. Scale bars: (a) 400 µm; (b) 500 µm; (c) 500 µm; (d) 500 µm; (e) 300 µm; (f) 100 µm.

Figure 11. Distribution map of Parastenonia parae and P. carajas sp. nov.: (a) South America; (b) Northern of Brazil. Pará state highlighted in grey; (c) Iron-ore outcrop in the Pará state; (d) Satellite image of the iron-ore outcrop where the caves were sampled.