Rayforstia lordhowensis Rix & Harvey, 2010

Rix, Michael & Harvey, Mark, 2010, The spider family Micropholcommatidae (Arachnida: Araneae: Araneoidea): a relimitation and revision at the generic level, ZooKeys 36 (36), pp. 1-321 : 57-58

Rayforstia lordhowensis Rix & Harvey , sp. n.

urn:lsid:zoobank.org:act:F924C5AC-108D-4E75-AC69-8B1818440781

Figs 87E , 88–89 , 216

Type material. Holotype male: next to Soldier’s Creek , Lord Howe Island, New South Wales, Australia, litter, 31°34'55"S, 159°05'09"E, 8.VI.2003, I. Hutton, K. Lees ( AMS KS88916 ).

Paratypes: Allotype female, Stephens Reserve , New Settlement, Lord Howe Island, New South Wales, Australia, pitfall trap, 31°31'33"S, 159°03'53"E, 4–14.XII.2000, AM team ( AMS KS76260 ) .

Etymology. The specific epithet refers to the type locality of this species.

Diagnosis. Males of Rayforstia lordhowensis can be distinguished from all other described congeners except R. raveni by the absence of a dorsal scute ( Figs 88 A–B); and from R. raveni by the shorter embolus and more symmetric, triangular conductor ( Fig. 89 ). Females can be distinguished from all other described congeners by the tilted, globular morphology of the spermathecae ( Fig. 87E ). Both sexes can also be recognised by the small body size and Lord Howe Island distribution (Fig. 216).

Description. Holotype male: Total length 0.68. Carapace 0.34 long, 0.27 wide. Abdomen 0.36 long, 0.25 wide. Leg I femur 0.25. Body colour very pale cream. Carapace raised anteriorly, not fused to sternum except around petiole; dorsal surface of pars cephalica slightly convex in lateral view. Eyes present on anterior margin of pars cephalica, but barely-visible due to faded colour of specimen. Chelicerae without bulging anterior projections; promargin with three peg teeth. Legs relatively short (leg I femur-carapace ratio 0.74); macrosetae absent. Abdomen oval, covered with hair-like setae; dorsal scute and lateral sclerotic strips absent. Pedipalpal patella with retrolaterally-directed, hooked lRPA and rounded, depressed distal region with ornate, ridged cuticular microstructure; tegulum smooth, with excavate ETR and triangular distal conductor; embolus long (length> 5× width), looping dorsal to conductor ( Fig. 89 ).

Allotype female: Total length 0.86. Carapace 0.41 long, 0.31 wide. Abdomen 0.49 long, 0.37 wide. Leg I femur 0.28. Body colour very pale cream. Carapace raised anteriorly, not fused to sternum except around petiole; dorsal surface of pars cephalica slightly convex in lateral view. Eyes present on anterior margin of pars cephalica, but barely-visible due to faded colour of specimen. Chelicerae without bulging anterior projections; promargin without peg teeth. Legs relatively short (leg I femur-carapace ratio 0.68); macrosetae absent. Abdomen oval, covered with hair-like setae; dorsal scute and lateral sclerotic strips absent. Pedipalp entire, five-segmented. Epigyne with distinctive external morphology ( Fig. 88D ); spermathecae globular, tilted mesally; insemination ducts looped; fertilisation ducts sinuous ( Fig. 87E ).

Distribution. Known only from Lord Howe Island in the western Pacific Ocean, 780 km north-east of Sydney (Fig. 216).

Remarks. Rayforstia lordhowensis seems more similar to Australian species of Rayforstia than to New Zealand taxa, as evidenced by the absence of a dorsal scute on the male abdomen and the close similarity to R. raveni from eastern Australia. The species is found on both the north and mountainous south of Lord Howe Island ( Fig. 220 ); the habitat at Stephens Reserve is lowland, subtropical rainforest dominated by Kentia palms ( Howea spp.) ( Fig. 220F ). It is the smallest known species of Rayforstia .

Figures

Figure 87. Rayforstia species, female cleared receptacula, dorsal view: A–B R. vulgaris (Forster) from Lewis Pass, New Zealand (WAM T94455) C R. signata (Forster) from the Puhipuhi Valley, New Zealand (AMNH) D R. antipoda (Forster) from Lake Hawea, New Zealand (AMNH) E allotype R. lordhowensis sp. n. from Lord Howe Island, New South Wales (AMS KS76260) F R. propinqua (Forster) from Broken River, New Zealand (MCZ) G R. salmoni (Forster) from Desert Road, New Zealand (AMNH) H R. scuta (Forster) from Norsewood, New Zealand (AMNH). Arrows indicate the trajectory of insemination ducts. Scale bar = 0.065 mm (65 µm).

Figure 88. Rayforstia lordhowensis sp. n. from Lord Howe Island, New South Wales.A, C holotype male (AMS KS88916): A habitus, dorsal view C cephalothorax and pedipalps, ventral view. B, D allotype female (AMS KS76260): B habitus, dorsal view D abdomen, ventral view. Note the pale body colouration.

Figure 89. Rayforstia lordhowensis sp. n., holotype male from Lord Howe Island, New South Wales (AMS KS88916): A left pedipalp, ventral view B left pedipalp, retrolateral view. Scale bar = 0.065 mm (65 µm).

Figure 220. Lord Howe Island, western Pacific Ocean – home to three genera of Micropholcommatidae, including Patelliella adusta sp. n., the only known member of the tribe Patelliellini. A view across Lord Howe Island from Kims Lookout, showing southern mountains in the distance B Mount Lidgbird and Mount Gower from Transit Hill, showing cloud-covered summits C–E fern- and moss-covered vegetation on the summit of Mount Gower, habitat of P. adusta F lowland kentia palm rainforest at Stephens Reserve, habitat of Rayforstia lordhowensis sp. n. Images by M. Rix.