Phthirocoris mirabilis n.sp.
Head, pro- and mesothorax and most of the anterior legs rusty brown; haustellum, antennae, metathorax, mid and hind legs paler. Apex of femora and base of tibiae in anterior legs, base and apex of femora, base and apex of tibiae and tarsi in mid and hind legs, pale testaceous. In the female (in mounted specimens), abdomen pale yellow brown, with sternites of segment 7 pale testaceous; in the male, all segments light rusty brown, intersegmental areas paler. Vestiture consists of testaceous hair of average length disposed evenly over the whole insect, with a few outstanding elongate hairs on the antennae, especially the terminal segment, tibiae and tarsi, and some very long hairs on the seventh and eighth abdominal segments.
Imago. Apterous. Eyes simple, flattened, with paired ommatidia, ocelli absent. Head slender, elongated, narrow, transverse suture behind the eyes pronounced, behind this suture somewhat swollen and rounded. Haustellum 4-segmented. Antennae 4-segmented, attached to the external anterior margin of head, the bases of segments 2–4, and less so in 1, constricted there and giving the appearance of additional minute segments. Clypeus long and narrow; labrum elongate-triangular, rounded anteriorly. Thorax irregular in form (Figs. 1 and 2), a little longer than head and haustellum together; prothorax roughly hexagonal, constricted at the anterior third, with vestiture comprising a fairly evenly distributed covering of long hairs, shorter dorsally and ventrally than laterally, where they and a similar dorsal posterior zone of hairs are mounted on annular elevations; mesothorax narrowed anteriorly, regularly broadening laterally to the posterior margin, dorsally evenly rounded and not much wider anteriorly than posteriorly, with a large transverse ellipsoidal elevation occupying most of the dorsal surface, vestiture dorsally and laterally consisting of longer and stouter hairs than those on the prothorax, nearly all mounted on annular elevations; metathorax narrowed evenly from anterior quarter forwards, otherwise parallel-sided, rounded at posterior angles, quadrately elevated dorsally, vestiture and its mounting similar to that of mesothorax, but devoid of hairs ventrally. Legs stout, with characteristic differences well illustrated in Figs. 1 and 2; anterior coxae large, rounded, contiguous; median coxae smaller,
greatly curved internally, nearly straight externally, separated; hind coxae narrower and elongate with the internal curvature less apparent, separated; anterior tibiae with transverse fimbriate pecten, several long heavy spines and curved sensory bodies at anterior margin below, tarsi 1-jointed, with long heavy spines and curved sensory bodies below, claws simple, very long and strong; mid tibiae with much reduced fimbriate pecten below, which is divided into two parts by the presence of two long, heavy spines, tarsi 2-jointed, the first joint minute and prolonged forwards under joint 2, claws simple, smaller; hind tibiae with fimbriate pecten and spines similar to those of mid tibiae, but with inferior part of pecten having very short spines, tarsal claws similar to those of mid tarsi. Abdomen of eight segments, male hypopygium prominent, with eight very long hairs, in addition to normal vestiture.
Length, imago, including haustellum, ca. 4·4 mm. (♀), ca. 4 mm. (♂).
Nymph. Apterous. All tarsal segments undifferentiated and therefore appearing single; not much modified in other characters from those of the imago, excepting that the hair covering is weaker and pigmentation is almost lacking.
Length, including haustellum, 2·5–2·75 mm.
Material. Holotype ♂ and Allotype ♀, 5 male paratypes, 14 female paratypes and 10 nymphs, upper Maitai River valley, Nelson, 3.4.50, in the collection of the Cawthron Institute; 4 male and 10 female paratypes, upper Maitai River valley, 18.2.50, 2 female paratypes, same locality, 1.2.44, in the writer's collection. The whole of the above material was collected by the writer from forest floor leafmould, taken in cool, moist situations. All specimens are mounted on slides.
This species differs from P. antarcticus Enderlein (Fig. 3) principally in the flattened eyes with two ommatidia, situated halfway along the head, the presence of a pronounced suture behind the eyes, and the markedly swollen nature of the head posteriorly, also the eight segmented abdomen. The size of the eggs within the female is relatively larger, as is shown (Fig. 1) by two ruptured examples.
The loose articulation of the prothorax with the mesothorax is remarkable and gives P. mirabilis an extraordinary amount of mobility, which is apparent when watching it walk around any small obstacle. The abdominal colouring in living specimens is deep cream, tinted brownish by the pigment of the derm, particularly in the males. With the polyvinal alcohol mountant used for the preparation of most of the specimens examined, extrusion of the head beyond the thorax and of the prothorax beyond the mesothorax is to be seen in Figs. 1 and 2, in both instances lending an unnatural appearance to the insect; these exposed parts therefore are not mentioned in the description.
The specimens from which Enderlein drew up his descriptions of P. antarcticus in 1904 and 1909 were obtained on the Crozet Islands and some of them were obtained from moss. With the record of P. mirabilis from New Zealand, the range of this remarkable apterous genus, represented now only by these two described species, is greatly
extended and substantiates still further the subantarctic land bridge theory, which accounts for so many similarities in the faunas and floras of New Zealand and other southern land masses. It remains now to discover additional Phthirocoris species to connect this linkage and they may yet be represented in the south of New Zealand, Stewart Island, the Snares Islands, Auckland Islands, Kerguelen Island, the Falkland Islands and Patagonia in South America.
[Footnote] † Breddin, Mitt. Nat. Mus., Hamburg, 22, p. 142, 1905.
[Footnote] * Bergroth, Wien. Ent. Zeit., 25, p. 6, 1906; Ann. Mus. Nat. Hung., 4, p. 326, 1906