Hypogastrura promatro (Wray, 1950)

Bernard, Ernest C., 2015, Redescriptions of Hypogastruridae and Onychiuridae (Collembola) described by David L. Wray, Zootaxa 3918 (3), pp. 301-338 : 316-319

Hypogastrura promatro (Wray, 1950)

Figs. 10 , 11

Achorutes promatro Wray 1950: 94 .

Hypogastrura promatro Salmon 1964: 225 ; Christiansen & Bellinger 1980: 75, 1998: 77. Hypogastrura utahensis ( Wray, 1953) new synonym (p. 4).

Specimens examined. Lectotype male, three paralectotypes (1 male, 2 juveniles) (by present designation) of H. promatro , USA, Idaho, Franklin, 2 November 1949, Colorado blue spruce, G. F. Knowlton, coll.; 1 paralectotype, USA, Utah, Cache County, Amalga, 2 November 1949, ash ( Fraxinus sp.), G. F. Knowlton, coll.; lectotype female (by present designation) of H. utahensis , USA, Utah, Ogden, 13 May 1949, on grass, G. F. Knowlton, coll.

Redescription. Length of H. promatro males up to 1.28 mm, H. utahensis length 1.38 mm [ H. promatro up to 1.0 mm, H. utahensis up to 1.5 mm]. [Color of H. promatro light grayish to grayish blue, sometimes grayish red, speckled and spotted with reddish purple spots; H. utahensis white with a faint pale greenish tinge.] Granulation moderate, granule width 3.0–3.6 Μm; Yosii’s “a” number 8–11. Typical head and body setae short, smooth, becoming slightly longer posteriorly, longest abdominal setae sparsely and weakly serrated ( Figs. 10 A, B). All head setae normally present. Sensilliform setae of thorax and abdomen approximately twice the length of neighboring p-setae. Pronotum with three setae on each side, outermost seta slightly longer than more medial setae. Mesonotum with seta m2 and extra seta m3’ between m and p-rows; seta m5 absent. Metanotum lacking setae m2, m3’ and m5, m4 sometimes absent. Abdominal terga I–III with seta a3, lacking a4; m-row composition variable Seta a3 and m2 absent on Abd. IV, a4 rarely doubled, m4 position variable; p1 and p2 lengths equal. Three rows of setae on Abd. V; seta p1 equal to or slightly longer than p2. Plurichaetosis infrequent, with occasional doubling of a-row setae.

Antennal segment IV with simple apical vesicle and five sensilla, four dorsal and lateral, one ventral ( Figs. 11 C, D). Subapical organite minute, pointed, nearly apical; microsensillum elongate-oval, in pit. Dorsal and lateral setae sensilliform except one shorter typical seta in middle. Ventral side of Ant. IV ( Fig. 11 D) without distinct sensory field but with about 10 loosely grouped microchaetae; other setae of ventral side typical pointed setae, not sensilliform. Sense organ on Ant. III with two smooth, rounded sensilla flanked by longer sensilla; microsensillum a thin rod ( Fig. 11 C). First antennal segment with 7 setae, Ant. II with 12 setae.

Ocelli 8+8. Postantennal organ ( Figs. 11 A, B) with four small, equal lobes, slightly wider than diameter of nearest ocelli; exceptionally PAO with three lobes; surface of lobes variably punctate. Accessory tubercle absent. Labrum not seen clearly. Maxilla head ( Fig. 10 C) with prominent, bifurcated lamella 1, strongly toothed lamella 2 and broad lamella 4 nearly as long as lamella 2. Outer lobe of maxilla with two sublobal hairs. Labial palpus ( Fig. 11 E) with slender sensilla equal to or longer than guard setae; a1 and b1 elongate-conical, not on raised bases; b2, d2 and e2 linear, not spine-like, on conical bases; other guard setae elongate-sensilliform; d1 and e7 absent. Labial palpus with 6 proximal setae.

Tbiotarsi I, II, III with 19, 19, 18 setae, respectively; one clavate tenent hair ( Figs. 11 F, G). Unguis with small inner tooth and pair of minute distal teeth. Unguiculus with small basal swelling and tapering apical filament reaching inner tooth.

Ventral tube with 4+4 setae. Tenaculum with 4+4 teeth, without setae. Dens 3‒3.5× length of mucro, dorsally with strong tubercles arranged in longitudinal rows ( Figs. 11 H, I); seven slender, smooth setae, the outer proximal seta the longest. Mucro slender, tapering, terminating in rounded or recurved tip ( Figs. 11 H–K), tip broken off one H. utahensis mucro; thin, rounded, medial lamella present. Anal spines small, straight, on short basal papillae ( Figs. 10 A, B), one-third to one-half length of inner unguis.

Remarks. Hypogastrura promatro is a member of the H. manubrialis group. The types of H. promatro and H. utahensis are very similar in morphology and chaetotaxy, with only minor differences in abdominal m-row setal locations. All of the type specimens are from the contiguous states of Colorado, Idaho, and Utah. Hypogastrura utahensis was distinguished from H. promatro on the basis of having a trilobed postantennal organ ( Christiansen & Bellinger 1980, 1998). The type specimen of H. utahensis has one PAO with three lobes and one PAO with four lobes ( Fig. 11 B). Therefore, H. utahensis is synonymized here with H. promatro . Specimens of H. utahensis from British Columbia ( Christiansen & Bellinger 1980, 1998) need to be reevaluated to establish their identity.

Based on this reexamination of type specimens, H. promatro keys to H. christianseni Yosii, 1960 in Christiansen & Bellinger (1980, 1998). The two species appear to be nearly identical and occupy the same general range in the northwestern states of the U.S., but possible synonymy must await study of H. christianseni type material. Christiansen & Bellinger (1980, 1998) considered H. christianseni and H. utahensis to be closely related based on the presence of the m-seta row on Abd. V. Types of H. promatro also have the m-seta row but this character was not known to Christiansen & Bellinger due to the unavailability of type specimens. Christiansen & Bellinger (1980, 1998) suggested that H. promatro was possibly synonymous with H. pannosa ( McNamara, 1922) (synonymized with H. assimilis ( Krausbauer, 1898) by Babenko et al. 1994), but H. assimilis lacks m-row setae on Abd. V.

In Babenko (1994) and Thibaud et al. (2004) H. promatro will key to H. vernalis ( Carl, 1901) . The two species are very similar and H. promatro could be a junior synonym of H. vernalis . Based on the many descriptions of H. vernalis ( Babenko 1994, Fjellberg 1998, Stach 1949, Thibaud et al. 2004), the two taxa vary in the presence of lateral ungual teeth (present in H. promatro , absent in H. vernalis ) and unguicular shape (tapering in H. promatro , with apical filament in H. vernalis ).

Figures

FIGURE 10. Hypogastrura promatro. A) Dorsal chaetotaxy, lectotype; closeup: anal spines and serrate terminal setae. B) Dorsal chaetotaxy, holotype of Achorutes utahensis. C) Head of maxilla, capitulum teeth not illustrated.

FIGURE 11. Hypogastrura promatro. A) Postantennal organs (PAO), lectotype. B) PAOs and anterior eyes, lectotype of Achorutes utahensis. C) Third and fourth antennal segments, dorsal view. D) Fourth antennal segment, ventral view. E) Labial palpus. F) Distal tibiotarsus, lectotype. G) Foot, lectotype of A. utahensis. H) Dentes and mucrones, dorsal view. I) Dens and mucro, lateral view. J) Mucro in subdorsal and lateral views. K. Mucrones of A. utahensis lectotype.