Entomobrya intermedia Brook, 1883

Katz, Aron D., Giordano, Rosanna & Soto-Adames, Felipe, 2015, Taxonomic review and phylogenetic analysis of fifteen North American Entomobrya (Collembola, Entomobryidae), including four new species, ZooKeys 525, pp. 1-75 : 32-33

Taxon classification Animalia Collembola Entomobryidae

Entomobrya intermedia Brook, 1883 Figs 2, 21, 22, 39

Description.

Body shape and color pattern. Body oval and cylindrical. Color pattern monomorphic (Fig. 21): yellow background with black, dark brown or purple pigment forming two incomplete, broken, longitudinal bands from Th. 2 through Abd. 3 and a conspicuous W-shaped mark on Abd. 4. Usually with dark pigment covering the lateral margins of the head. Antennae light brown or purple becoming increasingly dark towards the apex.

Head. Apical bulb of 4th antennal segment simple. Long differentiated smooth setae on ventral side of 1st antennal segment ≈5 × short setae. Prelabral setae ciliate. Ornamentation of the distal margin of the labral papillae with 2-4 small spine-like projections (Fig. 2). Lateral appendage of labial papilla E slightly curved, thin, nearly reaching tip of papilla. Dorsal head chaetotaxy (Fig. 22A) with macrosetae An’ 0, A3a2, A3a3, M3i, S’ 0, S4i, S6, Ps3, Pi1, and Pm1i absent; an additional macroseta external to A3 present in some specimens; S1 and Pm1 usually present, but may be asymmetrical. Eyes G and H small and subequal. Eye patch with 5 setae.

Thorax: Thoracic chaetotaxy well-developed and relatively stable. Th. 2 macrosetae a5, m1, m2, m2i, m4, m4p, m4i, and m5 present (Fig. 22B). Lateral sensilla obscured in all specimens examined. Posterior macrosetae (series P) present. Th. 3 macrosetae a1, a2, a3, a4, a4i, a5, a6, m4, m5, m5i, and m6 present (Fig. 22C). Posterior macrosetae (series P) present. The chaetotaxy of zone Pm with a moderate number of supplemental macrosetae in both thoracic segments (Fig. 22B,C). Typical sensilla present (not shown in figure).

Legs. Trochanteral organ with triangular setal pattern and up to 31 setae. Unguis with 4 internal teeth; basal teeth located approximately middle of inner claw length.

Abdomen. Abdominal chaetotaxy stable. Abd. 1 with 7 macrosetae (Fig. 22D). Abd. 2 macroseta a2, a3, m3, m3e, and m5 present (Fig. 22E). Abd. 3 with macrosetae a1, m3, am6, pm6, and p6 (Fig. 22F). Abd. 4 with 9-10 inner macrosetae (Fig. 22G). Mucronal teeth subequal. Typical sensilla present (not shown in figure).

Remarks.

Entomobrya intermedia can be easily identified by the presence of two longitudinal stripes, a W-shaped mark on Abd. 4 combined with the presence of Th. 2 macrosetae m5 and Abd. 3 a1, and the absence of head macrosetae S4i, Abd. 2 m3ep, and Abd. 3 a2 (see Table 2 for additional diagnostic characters). Historically, this species was considered a synonym of Entomobrya nivalis . However, the clear differences in chaetotaxy (see Table 3) and color pattern separate Entomobrya intermedia from Entomobrya nivalis and other similar forms such as Entomobrya multifasciata and female Entomobrya atrocincta . Furthermore, molecular data supports the separation of this species from Entomobrya nivalis ( Katz et al. 2015). The combination of chaetotaxy outlined in Table 3 should be used in conjunction with color pattern characters to differentiate this species. Note that observation of chaetotaxy was only examined for specimens collected from Chester County, Pennsylvania. It is likely that specimens from additional localities may re veal more variation in chaetotaxy than described here, especially since the chaetotaxy reported in Palearctic specimens ( Jordana 2012) is different than those observed in North American specimens.

Distribution.

North America and Europe. The actual distribution of Entomobrya intermedia in North America is unclear, as before Christiansen and Bellinger’s (1998) monograph the species was included within Entomobrya nivalis ( Christiansen 1958b). In fact, some records of Entomobrya nivalis , Entomobrya multifasciata and female Entomobrya atrocincta , regardless of date, may actually refer to Entomobrya intermedia . Suppl. material 1: G shows the distribution of Entomobrya intermedia in North American as currently understood.

Material examined.

USA: 2 on slides, Pennsylvania, Chester Co., Wayne, sweep of Forsythia sp., 23.v.2011, AK11-32; 8 on slides, 12 in vial, Pennsylvania, Chester Co., Wayne, sweep of Forsythia sp., 29.vi.2012, AK12-50.