Brochopeltis mediolocus Mesibov

Mesibov, Robert, 2015, Redescription of Brochopeltismjoebergi Verhoeff, 1924 and description of a second Brochopeltis species from Australia (Diplopoda, Polydesmida, Paradoxosomatidae), ZooKeys 504, pp. 59-73 : 64-69

Taxon classification Animalia Polydesmida Paradoxosomatidae

Brochopeltis mediolocus Mesibov sp. n. Figs 2B, 6, 7; Fig. 4 (map)

Holotype.

Male, Anzac Parade (turf farm), Middle Point, NT, -12.5677 131.319 ± 200 m, 18 February 2015, M. Neal, ex ground at edge of pasture, MAGNT NTM-M000056.

Paratypes.

NTEIRC: 2 males, details as for holotype, 63897; 5 females, 13 juveniles, details as for holotype, 63898; 1 male, same details but 16 February 2015, in large numbers on ground, 63895.

Other material.

NTEIRC: 5 females, 117 juveniles (collected with types, not examined; see Suppl. material 1 for details).

Diagnosis.

Differs from Brochopeltis mjoebergi in distal portion of gonopod telopodite bent but directed distally, not curving in wide spiral; with dorsum uniform in colour, not with pale, paramedian longitudinal bands and pale paranota on a darker background; and with tarsal brushes on all male legs except last two pairs, rather than on legpairs 1-7 only.

Description.

Male/female approximate measurements: length 29/30 mm, midbody paranota width 3.6/3.8 mm, prozonite width 2.7/3.0 mm, maximum vertical diameter 2.6/3.0 mm. Live, well-coloured animals more or less uniformly dark brown in body colour, shiny (Fig. 6A). In alcohol, body colour brown (Fig. 6B, C), darker on paranota and posterior metazonite margin, lighter ventrally and in pleural keel area; head and antennae dark brown with lighter spot just above antennal socket; legs darker than body.

Male with vertex and frons almost bare, clypeus sparsely setose; vertigial sulcus distinct, ending at dorsal level of antennal sockets; post-antennal groove moderately deep; antennal sockets separated by ca 1.3 × socket diameter. Antenna filiform, reaching dorsally to rear of ring 3; antennomeres with relative lengths (2=3)>(4=5)>6 and with 5 and 6 subequal in apical width. Head slightly narrower than collum in dorsal view, both narrower than ring 2; rings 2-17 subequal in width. Collum D-shaped in dorsal view, the lateral margin lifted slightly as a narrow paranotum, posterior corner rounded. Paranota on haplo- and diplosegments with margins thickened dorsally, so that dorsal paranotal surface appears slightly depressed. Ring 2 paranotum (Fig. 7A) with lateral margin lower than lateral margins of collum and ring 3 paranota; subtrapezoidal with rounded corners, extended slightly anteriorly and posteriorly. Ring 3 paranotum shorter than ring 2 paranotum; posterior corner extending posteriorly, rounded. Ring 4 paranotum intermediate in length between paranota of rings 2 and 3; posterior corner slightly extended posteriorly. Paranota on diplosegments 5-17 (Fig. 6B, C) set at ca 1/2 ring height; anterior corner strongly rounded; lateral margin further from the body posteriorly, thicker on pore-bearing rings; posterior corner rounded, progressively extending further posteriorly and passing posterior metazonite edge from about ring 10. Paranota greatly reduced but still prominent on rings 18, 19. Pleural keels (Fig. 7B) distinct on rings 2-8, reduced posteriorly to progressively smaller bulges, not detectable on rings 16-19; keels on rings 3-8 with well-defined lateral margins with posterior corners projecting a little posteriorly. Prozonites and metazonites (Fig. 6B, C) smooth, bare; transverse furrow at ca 1/2 metazonite length, distinct, extending laterally to paranotal base; waist short, shallow, not obviously sculptured; limbus a narrow, thin, continuous sheet. Pore formula normal; ozopore small, round, opening laterally on thickened paranotal margin almost at level of posterior metazonite margin. Spiracles on diplosegments above and just anterior to leg bases; anterior spiracle subquadrangular, posterior spiracle subtriangular; spiracular rim low, filter slightly emergent, forming rounded fold in inverted, tight U-shape in spiracular opening. Midbody sternites very sparsely setose, as wide as long, transverse impression wider than longitudinal impression; no cones or projections on any sternites. Midbody legs with relative podomere lengths femur>>(tibia=tarsus)>(prefemur=postfemur); femur ca 1.7 × as long as tarsus; anterior leg prefemora only slightly swollen dorsally. Pre-anal ring sparsely setose; epiproct extending past anal valves, in dorsal view tapering and truncate, tip ca 1 /5 width of pre-anal ring; hypoproct rounded-trapezoidal; spinnerets in rectangular array, wider than long.

Leg 1 (Fig. 7C) with small, short, rounded process at ca 1/2 length of medial femur surface, directed mediodistally and slightly anteriorly. Gonopore small, round, opening on short distomedial bulge of leg 2 coxa. Sternal lamella (Fig. 7D) ca 90% of width between leg 4 bases, leaning slightly anteriorly; lateral margins straight, vertical; corners rounded; ventral margin medially incised. Dense brush setae on tarsi of all but last 2 legpairs, on some anterior legs also at distal end of tibia.

Gonopod aperture just wide enough to accommodate gonocoxae, 1/3-1/2 ring 7 prozonite width. Gonopod telopodites (Figs 2B, 3C, D) straight, parallel, reaching leg 7 bases when retracted; sternite between leg 7 bases slightly excavate. Rounded, transverse ridge just anterior to aperture on either side, the two ridges nearly confluent medially.

Gonocoxa short, the anterodistal surface with low, ridge-like protuberance bearing sparse, long setae on distal side. Prefemur large, C-shaped, the distal end projecting posterolaterally as rounded extension reaching ca 1/4 telopodite height; numerous long setae on posterior and posteromedial surfaces of prefemur. Cannula small, arising from gonocoxa apex. Telopodite beyond prefemur without branches, the basal half straight and slightly expanded distally; at ca 2/3 telopodite height, telopodite flattening slightly and curving anterolaterally, then constricting and bending sharply anteriorly, curving mediodistally and flattening further, the apical margin rounded distally with lateral margin produced as small triangle. Prostatic groove (Fig. 3C, D) running straight on medial surface of basal half of telopodite beyond prefemur, then following bends and curves of telopodite to open at tip of apical triangular projection.

Female without leg modifications; epigynum ca 1/4 ring 2 width, very slightly raised medially in small rounded triangle; cyphopods not examined.

Distribution.

So far known only from the type locality, a farm ca 50 km southeast of Darwin in the monsoon tropics of Australia (Fig. 4).

Name.

Latin medius, “middle”, + locus, “place”, for the type locality, Middle Point; noun used as adjective.

Remarks.

I am tentatively assigning this species to Brochopeltis not only because the gonopods are similar, but because Brochopeltis mediolocus sp. n. and Brochopeltis mjoebergi share two features which I have not yet noted in other Australian Antichiropodini . One is the lifting and extension of the lateral collum margins as paranota. The second possible synapomorphy is the pronounced dorsal thickening of paranotal margins.

The types were collected on a farm and it is possible that Brochopeltis mediolocus sp. n. is not locally native, but has been introduced to Middle Point from elsewhere in tropical Australia. The only previous record of Paradoxosomatidae from the northern portion of the Northern Territory ( Australia’s "Top End") is of the introduced Asian species Orthomorpha coarctata (De Saussure, 1860) in urban Darwin ( Jeekel 1982).