Heteraphorura magnina (Wray, 1950) Wray, 1950

Bernard, Ernest C., 2015, Redescriptions of Hypogastruridae and Onychiuridae (Collembola) described by David L. Wray, Zootaxa 3918 (3), pp. 301-338 : 330-332

Heteraphorura magnina (Wray, 1950) new combination

Figs. 19 , 21 D–F

Onychiurus magninus Wray 1950: 91 .

Onychiurus (Protaphorura) magninus Christiansen & Bellinger 1980: 432 ; 1998: 475.

Specimens examined. Neotype female (by present designation), USA, Utah, Logan Canyon, 28 October 1955, in moss, G. F. Knowlton, coll.; female, USA, Idaho, Franklin, 1 April 1959, poplar leaves, G. F. Knowlton, coll.

Redescription. Length of specimens 1.9 mm, 2.4 mm [up to 3 mm]. [Color white.] Body parallel-sided; Abd. VI elongated, tapering ( Fig. 19 A). Granulation on head distinct, granule diameter 2.3–3.0 Μm. Each body tergite in anterior three-fourths with fine granules not arranged in distinct rows and separated from other granules by more than their own diameter, granule diameter 1.8–2.5 Μm; granules of posterior fourth of each tergite in densely packed transverse rows, diameter 1.5–1.9 Μm. Anal spines conical, slightly curved dorsad, on short papillae ( Fig. 21 F). Dorsal chaetotaxy differentiated primarily into macro- and mesosetae; plurichaetosis moderate. Sensillumlike setae not distinct from normal setae. Cephalic seta d0 present. Lateral microsensilla present on mesonotum and metanotum. P-row setae generally longer than a- and m-row setae. Seta m0 present on tergite V ( Fig. 20 A); setae a0 and p0 present on tergite VI ( Fig. 21 E). Thoracic sterna without setae. Venter of Abd. VI terminus with five asetae and three extra setae of similar length; setae b0 and b1 of similar length; c-setae shorter than b-setae ( Fig. 21 F).

Antennal bases distinct, with weaker granulation than rest of head ( Fig. 19 E). Dorsal pseudocellus formula 40/ 011/11035; four antennal pseudocelli flanked by small pseudocellus-like structures not surrounded by larger granules ( Fig. 19 E); subcoxal pseudocelli not observed; ventral pseudocelli absent. Parapseudocelli and pseudopores not observed.

Antennal segment IV without apical vesicle or cauliflower-like protuberances ( Fig. 19 C). Most setae slender, sensillum-like. Subapical organite weakly clavate. Microsensillum a blunt peg in pit in the proximal third of Ant. IV. Sense organ of Ant. III with five guard setae, five papillae, two smooth sense rods, and two stalked, oval, morel-like (mulberry-like) sense clubs; microsensillum nearly level with papilla base ( Fig. 19 D). Antennal segments I, II, III with 10, 17, 16 typical setae, respectively. Labrum not clearly seen. Maxilla ( Fig. 21 D) with bifurcated lamella 1 extending past capitulum teeth; lamella 2 reaching tips of teeth, denticulate on both edges; lamella 4 extending above 3, 5 and 6, its face covered with minute denticles. All sensilla of labial palpus present, sensilla A and C blunt (AC type) ( Fig. 19 F); guard setae a1, b1, b2 and d2 spine-like on short papillae, a1 longer than the others; guard setae b3 and b4 weakly spatulate, other guard setae pointed; d1 and e4–e7 absent; six proximal setae, most lateral seta straight, other five slender, curved. Postantennal organ with nine simple or bilobed vesicles arranged mostly obliquely to axis or organ, set in elongated oval groove ( Fig. 19 B).

Tibiotarsi I and II with 3 setae in proximal whorl, 8 setae in middle whorl, and 11 setae in distal whorl; tibiotarsus III with 2 proximal, 7 middle, and 11 distal setae. Unguis untoothed, granulate basally; unguiculus granulate basally with weak basal lamella, apical filament tapering and extending past middle of ungual inner margin ( Fig. 19 G). Tenent hair of moderate length, pointed. Ventral tube with 2 basal and 6–8 distal setae. Furcular region oval, finely granulated, with four posterior setae irregularly arranged in two rows or as an arch ( Fig. 19 H); manubrial setae irregularly distributed.

Remarks. Type specimens of H. magnina were not located in the Wray collection, but a female from the type locality and a female from Franklin, Idaho (distance between sites about 32 km), labeled in Wray’s hand, were found and used for the redescription. The female from the type locality is designated as the neotype.

Heteraphorura magnina new combination probably is a member of the “ subtenuis ” complex ( Christiansen & Bellinger 1998, Part 2, p. 482, Table XVIII). Species in this complex are separated by the male ventral organ, which is unknown in H. magnina . This species differs from the other subtenuis complex members in having four distinct pseudocelli near each antennal base, rather than three, and in lacking an inner ungual tooth (present in the other species). In the key to North American Heteraphorura spp. ( Pomorski 2002), H. magnina will trace to H. justynae Pomorski, 2002 . The two species differ significantly in numbers of pseudocelli: H. magnina has 4+4 pseudocelli near the antennal bases, 3+3 on Abd. IV and 5+5 on Abd. V; H. justynae has 2+2, 2+2 and 3+3 pseudocelli, respectively. Wray’s specimens key easily to Onychiurus (Protaphorura) magninus in Christiansen & Bellinger (1980, 1998).

Figures

FIGURE 19. Heteraphorura magnina. A) Dorsal chaetotaxy; d 0 = unpaired median seta. B) Postantennal organ; sb = setal base. C) Tip of antenna. D) Sense organ of third antennal segment. E) Antennal base pseudocelli and accessory structures (as). F) Labial palpus. G) Apex of hind tibiotarsus. H) Ventral view of fourth abdominal segment.

FIGURE 20. Leeonychiurus mai. A) Head, prothorax, mesothorax of female, dorsal view; d 0 = unpaired median seta. B) Metanotum of male, dorsal view. C) Abdominal segments of female, dorsal view. D) Postantennal organ. E) Optical crosssection of postantennal organ. F) Tip of antenna. G) Sense organ of third antennal segment and enlargement of sense club. H) Labial palpus. I) Anterior edge of labrum. J) Apex of hind tibiotarsus. K) Ventral view of fourth abdominal segment, female. L) Ventral view of fourth and fifth abdominal segments, male.

FIGURE 21. Onychiuridae. A – C) Leeonychiurus mai. D – F) Heteraphorura magnina. G ‒ J) Onychiurus wilchi. A, D, G) Maxillae. B, E, H) Dorsal terminus of sixth abdominal segment. C, F) Venter of sixth abdominal segment. I) Sense organ of third abdominal segment, sense clubs not shown. J) Distal part of hind tibiotarsus.