Thortus helmorei, Leschen & Chen & Harmer, 2024

Thortus helmorei sp. nov.

( Figs 9 View Fig , 19D View Fig )

Type material. HOLOTYPE: ♁ ( AMNZ), labelled: ‘NEW ZEALAND, ND Waipoua Forest , 10.i.1967, R. Rowe. By giant kauri. Litter. L 5787 // AMNZ36232 View Materials ’. PARATYPES (4; AMNZ, ANIC, NZAC). NORTH ISLAND: ND: 1 ( ANIC), Waipoua SF, Yakas Tree Tk., 350 m, 11-14.iv.1980, broadlf.-podocarp,A. Newton, M.Thayer [35°36.99′S 173°31.91′E], litter at bases of Metrosideros robusta trunks; 1, Waipoua Forest, 10 Jan 1967, litter by giant kauri, R.J. Rowe, 35°37′S, 173°33.067′E, AMNZ 36233; 2, Waipoua State Forest, SH12, 20 Sep 1977, rotten stumps trees, D.W. Helmore, [35°38.772′S, 173°33.321′E], NZAC 04235069, NZAC 04272548.

Diagnosis. Thortus helmorei sp. nov. is a unicolourous species with the eye composed of a single facet. The only known Northland species of the genus, it can be distinguished from other unifacetted species by the absence of abdominal postcoxal lines.

Description. Length 1.70–1.75 mm. Colour of body unicolourous red-brown, with lighter antennal club, mouthparts and legs. Body surface glabrous, microsculpture absent from most surfaces, very weak and present on ventral surfaces of the head, hypomeron and lateral portions of the abdominal ventrites. Dorsal setae golden, consisting of short slightly curved and suberect setae. Ventral surfaces with short and suberect setae; punctation ovate on head (more impressed than on frons) and prosternum, mesoventrite foveolate, strongly impressed, disc of metaventrite with punctures variable, more closely spaced than those on the central disc of the prosternum, punctation of abdominal ventrites 1 to 4 generally smaller or equal to those on metaventrite, setae longer at sides, punctation on ventrite 5 denser with a well-defined patch of posteriorly-directed setae. Head not lengthened with a relatively short gena that is subequal in length to antennomere 1; frons not greatly constricted, narrowed to a width equal to length of antennomere 1; supra-antennal ridge with well-developed rim, bead absent; vertex delimited anteriorly by a transverse crenulate line, anterior surface punctured, posterior surface glabrous with small punctures posteriorly; gular punctation deep and ovate, diameters about equal to those on sides of head. Eye consisting of a single facet. Antennomere 2 barrel-shaped, wider than long, antennomere 3 subconical, equal in length and narrower than 2 and longer and as wide than 4, proportions of antennomeres 4–8 about the same, antennomere 9 wider than 8 and narrower than 10 and 11, antennomere 10 transverse and about the same width as 11, antennomere 11 longer than 10, subequal to 9 and 10 combined. Pronotum transverse, pronotal length/width ratio ~0.92, widest at apical third; anterior margin convex; anterior angles obtuse, not projecting and rounded; lateral edges weakly convex, weakly curved anteriorly in anterior 1/4, gradually and weakly converging posteriorly; pronotal disc with punctation more or less uniform and more larger and foveolate towards base, shallow to sparse to weak in central disc (without a median glabrous strip), separated by a distance of up to 3 times their diameter at anterolateral areas and larger and closer at base; median impression absent; transversely depressed at basal 1/5; basomedial macropuncture vaguely indicated; posterolateral angles obtuse and rounded, not projecting posteriorly; posterior margin sinuate with scutellar lobe. Prosternal process with weak lateral marginal beads, without strong longitudinal depression medially, process subparallel-sided and slightly expanded posteriorly behind procoxae, apex rounded, width slightly narrower than procoxa, 0.5 times as wide as prosternum; procoxal cavity with weak anterolateral notch. Scutellary shield suboval and transverse, 1.9 times as wide as long. Elytra about 1.27 times as long as combined widths, about 1.11 times as greatest width of pronotum, about 1.54 times longer than length of pronotum; setation uniform consisting of relatively short slightly curved setae; humeral plica absent; parasutural stria absent; punctation less dense than pronotum, impressed near base. Metaventrital process with anterior margin curved, marginal bead weakly indicated at middle. Tarsi moderately slender, 5-5- 5 in female, 5-5- 4 in male, male protarsomeres 1–3 and mesotarsomere 1 with tenent setae; mesotarsomeres 1–3 of subequal lengths, mesotarsomere 5 subequal to tarsomeres 1–4 combined. First abdominal ventrite with broad rounded intercoxal process, postcoxal lines absent. Aedeagus with relatively moderately long parameres weakly articulated to phallobase, paramere about 2 times as long as wide; apices more or less acute with two microsetae, membranous extensions absent; basipenis about 2.29 times as long as distipenis; distipenis about 1.90 times as long as wide, lateral lobes not well separated, basal plate absent; internal sac (?) with a single endophallite.

Etymology. Rarely into the field but quietly working at his bench, Des Helmore, artist, former illustrator at the NZAC and friend of the first author, is honored with the specific epithet.

Distribution. South Island: ND ( Fig. 21 View Fig ).

Remarks. Thortus helmorei sp. nov. is known from five specimens, two collected from a rotten tree stump and litter at the base of a Metrosideros robusta A.Cunn. trunk.