Atelomastix bonhami, Mesibov, Robert, 2017

Mesibov, Robert, 2017, Iulomorphid millipedes (Diplopoda, Spirostreptida, Iulomorphidae) of Tasmania, Australia, ZooKeys 652, pp. 1-36 : 20-22

Atelomastix bonhami sp. n. Figs 9, 10A, C, D

Holotype.

Male, White Spur, Tas, -42.7764 146.0369 ± 100 m [label "DN 211 634" (= 55G 421100 5263400, AGD66)], 320 m a.s.l., 2 February 1994, R. Mesibov, QVM 23:54460.

Paratypes.

1 male, 1 female, details as for holotype, QVM 23:54176.

Other material.

7 males, 5 females and 5 juveniles from 7 unique localities in Tasmania; details in Suppl. material 1.

Diagnosis.

Most similar to Atelomastix gibsoni Edward & Harvey, 2010 from the Ravensthorpe Ranges in Western Australia; both species have a wedge-shaped sclerite “b” and a non-bifurcate sclerite “c”. Differences between Atelomastix bonhami / Atelomastix gibsoni : rounded tab present under sclerite “a” near pseudoflagellum/no tab; anterior corner of distal margin of sclerite “b” higher than posterior corner/anterior corner lower than posterior corner; sclerite “c” taller than sclerite “b” / sclerite “c” shorter than sclerite “b”.

Description.

Atelomastix as a genus has been well characterised by Edward and Harvey (2010), who described or redescribed 27 species from Western Australia. Atelomastix bonhami sp. n. fits the genus description and only key details are noted here.

Colour in alcohol variable, dark blueish grey to dark brown anteriorly on metazonites, pale posteriorly; some specimens largely brown. Ocelli 30-40 in 4-5 horizontal rows. Mature males with (37+5) rings, 2.0 mm midbody diameter to (60+1) rings, 2.3 mm. Longitudinal striae on metazonites meeting suture almost at right angle. Female substantially more robust than male with similar ring number, e.g. male with (51+1) rings, midbody diameter 2.2 mm vs female with (52+1) rings, midbody diameter 2.8 mm, both in QVM 23:54140.

Male gonopod aperture with sides slightly raised (Fig. 9A). Anterior gonopods nearly touching along midline. Sclerite “a” (Fig. 10A) curving posteriorly with pseudoflagellum (Fig. 10A; ps) arising at ca 3/4 gonopod height, extending posteriorly and slightly distally and gradually tapering to rounded apex; a thin, rounded tab (Fig. 10A; t) arising just distal to pseudoflagellum origin along sclerite midline. Sclerite “b” arising medially at ca 1/3 gonopod height, ca 3x as wide distally as at origin, thickly lamellar with distal half slightly bent medially, the distal margin with rounded anterior corner, sloping posterobasally with small, rounded notch at posterior corner; a double row of small, short setae near distal margin. Sclerite “c” more or less cylindrical basally, the apex curving slightly anteriorly and spatulate, the concave surface facing anterolaterally; a few long setae on anterior surface of sclerite at level of sclerite “b” distal margin.

Posterior gonopods (Fig. 10C) appressed basally along midline, 1/3-1/2 anterior gonopod height. Each posterior gonopod basally conical, tapering and with anterolateral extension; extension slightly flattened with a few long, mediodistally directed setae near base of extension on posteromedial surface and a few short setae at ca 1/2 gonopod height on medial surface.

Leg 1 (Fig. 10D) with prefemur wider than long, slightly tapering, with triangular tab (Figs 9B, 10D; at) on anteromedial surface of prefemur; relative lengths of podomeres femur>prefemur>tarsus>postfemur>tibia; tarsus distally excavate on anteromedial surface; prefemur, femur and postfemur with a few small setae laterally. Legpair 1 clearly separated on coxosternite, the latter with a field of long setae anterolateral to each prefemur.

Posterolateral margin of preanal ring meets epiproct margin at obtuse angle, making anal valves appear more prominent in lateral view than in other Tasmanian Iulomorphidae (Fig. 9C).

Distribution.

Known from wet forest, rainforest and scrub over ca 1500 km2 in southwest Tasmania at elevations ca 300-1100 m (Fig. 7D).

Name.

For Kevin Bonham, Tasmanian malacologist and diligent millipede hunter, who collected this species at two remote sites in 2016; noun in the genitive case.

Remarks.

The posterior gonopod of Atelomastix bonhami sp. n. is similar to that of Atelomastix nigrescens as illustrated in figs 13, 14 and 118 of Edward and Harvey (2010), and leg 1 of Atelomastix bonhami sp. n. closely resembles leg 1 of Atelomastix solitaria as illustrated in fig. 2 of Jeekel (2009).

Jeekel (2009: figs 3, 4) does not show the Atelomastix solitaria anterior gonopod in lateral view, so the shapes of the sclerites are unclear. From Jeekel’s description of Atelomastix solitaria and his fig. 4, it appears that sclerite “c” is sharply bent with an acuminate apex, unlike the smoothly curving, apically rounded sclerite “c” of Atelomastix bonhami sp. n. and the following species, and is shorter than “b”, rather than longer as in Atelomastix bonhami sp. n. and the following species.