Rhopalorhynchus tenuissimus ( Haswell, 1884 )

Staples, David A., 2009, A new species of Rhopalorhynchus (Pycnogonida: Colossendeidae) from Lizard Island, North Queensland, Australia, Zootaxa 2051, pp. 62-68 : 67

Rhopalorhynchus tenuissimus ( Haswell, 1884)

Colossendeis tenuissima Haswell, 1884: 1029 –30, pl. LV1, figs. 5–8.

Rhopalorhynchus tenuissimus Flynn, 1919: 71 –72, pl. XV111, figs. 1–3. Rhopalorhynchus tenuissimum Stock, 1958: 125 ― Staples, 1982: 465 –467, fig. 5 A– J. Arango, 2003: 2737, fig. 6.─ Takahashi et al, 2007: 67 –69, fig. 3.

Material examined. Gladstone, Calliope R., Van Veen grab, code no. 321, P. Saenger, Queensland Electricity Generating Board. NMV J58390 , 3 males.

Remarks. This paper presents an opportunity to document additional characters and variability in proboscis morphology in material of R. tenuissimus gathered from the Calliope River and Auckland Creek, Gladstone. Amongst the otherwise ‘typical’ specimens represented in that collection reported on by Staples (1982), there were two males in which the proboscis basal ‘stalk’ marginally exceeded the length of the distal region (51% and 53%). Although the increase from the previous maximum of about 48% is minimal, these records demonstrate that dependence on the relative lengths of the basal stalk and inflated part to distinguish species is potentially unreliable. Genital pores are very small and distal-most on the ventral surface of coxa 2 of all legs. The oviger spines on segments 7 to 10 are arranged in three rows. The peculiar aspect of the damaged juvenile proboscis illustrated by Arango (2009: Figure A) is not typical of others that follow the orientation and morphology of the adults ( Staples 1982: Figure 5 G, H).