Amastigogonus insularis, Mesibov, Robert, 2017

Mesibov, Robert, 2017, A new and unusual species of Amastigogonus Broelemann, 1913 from Tasmania, Australia (Diplopoda, Spirostreptida, Iulomorphidae), ZooKeys 687, pp. 45-51 : 45-47

Amastigogonus insularis sp. n. Figs 1 B–D, 2

Holotype.

Male, Tasman Island, Tasmania, 55G 581536 521818 (GDA94) [-43.2419 148.0042 ± 100m], 210m a.s.l., 19 November 2005, S. Bryant + Hamish Saunders Memorial Island Survey Program personnel, pitfall, cliff mosaic, 5A, QVM 23: 46411.

Paratypes.

Tasmania: 1 male, 4 females, 1 juvenile, Schouten Island [-42.3131 148.2850 ± 2km], 23-26 September 1993, R. Taylor, QVM 2017:23:0047; 4 females, Tasman Island [-43.2384 148.0031 ± 500m], 3 June 2016, L. Gadd, 2017:23:0093; 5 females, Tasman Island, -43.2357 147.9996 ± 25m, 190m a.s.l., 21 April 2017, R. and L. O’Grady, under she-oak log, QVM 2017:23:0094.

Diagnosis.

Male leg 7 coxa not noticeably elongated or distally swollen; coxite process on anterior gonopod much shorter than telopodite, not protecting pseudoflagellum; pseudoflagellum as in A. peninsulensis Mesibov, 2017 but longer, extending just past telopodite tip.

Description.

As for the genus description ( Mesibov 2017, p. 5) with the following details: holotype male with (59+1) rings, 2.0 mm midbody diameter; paratype male with (51+2) rings, 1.6 mm; longest female (in QVM 23:0093) with (63+1) rings, 2.5 mm. Trunk rings dark grey with light annulus posteriorly and irregular, partly annular light markings on prozonite (Fig. 1D); striae on posterior metazonites reaching ca 1/2 ozopore height.

Male with cardo not deeper posteriorly (Fig. 1C). Leg 7 coxa not noticeably elongated or distally swollen. Prefemoral pad ca 1/2 femur length.

Coxite process on anterior gonopod (Fig. 1B) reaching ca 2/3-3/4 telopodite height, not protecting pseudoflagellum. Telopodite (Fig. 2) with slight medial thickening bordered by two rows of short setae behind pseudoflagellum, meeting near telopodite apex. Pseudoflagellum arising at ca 1/2 telopodite height, ca 1/2 telopodite width at base and only slightly narrowing distally; slightly sinuous, curving first posteriorly, then anteriorly, then posteriorly to terminate just distal to telopodite apex, the pseudoflagellum tip bent medially (Fig. 1B); prostatic groove running on anterior edge of pseudoflagellum to posterodistal portion of tip.

Distribution.

Schouten and Tasman Islands off the east coast of Tasmania (Fig. 3).

Name.

Latin insularis , insular; adjective.

Remarks.

As with the two known males, the Schouten Island females are smaller than their Tasman Island counterparts: (51+2)-(59+1) rings, 1.5-2.3 mm midbody diameter from Schouten Island, (47+2)-(63+1) rings, 2.3-2.7 mm from Tasman Island. Further, the pseudoflagellum tip in the holotype male from Tasman Island is slightly longer, broader and more medially directed than the tip in the Schouten Island paratype. These are minor differences and I regard the two forms as conspecific.

I doubt that A. insularis sp. n. is restricted to its two widely disjunct localities, ca 105 km apart. However, the only iulomorphid so far collected on Forestier and Tasman Peninsulas, just north of Tasman Island (Fig. 3), is A. peninsulensis Mesibov, 2017. Similarly, the only iulomorphid recorded from the Freycinet Peninsula (Fig. 3), just north of Schouten Island, is A. michaelsae Mesibov, 2017. The latter species is also the only iulomorphid known from Maria Island, halfway between Schouten and Tasman Islands (Fig. 3). I suspect that A. insularis sp. n. will be found in future in coastal habitats along the east coast of the Tasmanian mainland, and possibly also on Maria Island.