Entomobrya quadrilineata Bueker, 1939

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 : 47-48

Taxon classification Animalia Collembola Entomobryidae

Entomobrya quadrilineata Bueker, 1939 Figs 2, 13C, 33, 34, 39

Description.

Body shape and color pattern. Body very elongate and cylindrical. Color pattern monomorphic (Fig. 33); white or yellow background with black or dark blue or purple pigment forming two dark parallel longitudinal stripes extending from anterior margin of Th. 2 through posterior margin of Abd. 2. Dark pigment present along lateral margins of Th. 2 through Abd. 2, forming 2 additional lateral longitudinal bands. Abd. 3 and Abd. 4. with 2 angled bands. A small patch of dark pigment sometimes occurs medially on Abd. 3. An irregular and (and sometimes incomplete) transverse band present along posterior margin of Abd. 4. Abd. 5 with 2 small lateral patches of pigment sometimes forming 2 triangles. Abd. 6 usually pale, without dark pigment. Apex of femora usually with a patch of dark pigmentation. Antennae usually with some light brown or purple pigment, darkening near apex. Longitudinal bands usually present in juveniles.

Head. Apical bulb of 4th antennal segment usually bilobed. Long differentiated smooth setae on ventral side of 1st antennal segment ≈4 × short setae. Four prelabral setae ciliate. Ornamentation of the distal margin of the labral papillae with single seta or spine-like projection (Fig. 2). Lateral appendage of labial papilla E almost twice as long as papilla. Labial triangle chaetotaxy slightly irregular and atypical: M1, r, E, L1, L2, all ciliate; r significantly smaller than other setae; a supplementary ciliate seta sometimes present internal to M1, and relatively difficult to observe; A1-A5 smooth. Dorsal head chaetotaxy (Fig. 34A) with macrosetae An’ 0, An3a3, A6, S’ 0, S6, Ps3, and Pm1i absent; Pi1 sometimes present. Eyes G and H small and subequal. Eye patch with 5 or 6 setae.

Thorax. Thoracic chaetotaxy greatly developed, with high levels of variation and many supplemental macrosetae. Th. 2 zone A enlarged and sometimes merging with medial macrosetae forming a single, large patch of setae (Fig. 34B). Th. 3 macrosetae m4, m5p, a6i, and a7 absent (Fig. 34C). Both thoracic segments with zone Pm enlarged, with many supplemental macrosetae present forming wing-like patches and extending near anterior row (Fig. 34B,C). Th. 3 pseudopore displaced anteriorly, very close to macrosetae a1, a2, and a3.

Legs. Trochanteral organ with rectangular setal pattern and up to 41 setae.

Abdomen. Abdominal chaetotaxy highly developed. Row of microsetae along posterior margin present in all segments (not displayed in figure). Abd. 1 with 12-16 macrosetae (Fig. 34D). Abd. 2 macrosetae a2, a3, m3, m3e, m3ep, m3ep2, m3ea, m5, p5, and p 6 present (Fig. 34E); m3ei usually present. Abd. 3 macrosetae a2, a3, m3, am6, pm6, and p6 present (Fig. 34F); a1 absent. Abd. 4 elongate, with at least 25 macrosetae internal to bothriotricha T2 and T4 (Fig. 34G), but number of macrosetae extremely variable between individuals and even within single individuals (Fig. 16C). Pseudopores on Abd. 4 with asymmetric relative insertions with respect to macroseta and bothriotricha (Fig. 13C). Mucronal teeth subequal.

Remarks.

Entomobrya quadrilineata can be identified by the presence of 2 parallel longitudinal thoracic stripes combined with the presence of head macrosetae M3i and ps5 and the absence of Abd. 3 macroseta a1 (see Table 2 for additional diagnostic characters). This species is part of the Entomobrya bicolor complex. Many supplemental macrosetae and extreme setal variation make it difficult to separate species in this group using chaetotaxy and other traditional morphological characters. However, there are clear differences in color pattern which can be used to differentiate Entomobrya quadrilineata from Entomobrya decemfasciata and Entomobrya bicolor (Table 5); Entomobrya quadrilineata has a relatively stable and easily distinguishable color pattern and can be diagnosed by the presence of two parallel longitudinal stripes extending from the anterior margin of Th. 2 through the posterior margin of Abd. 2 (Fig. 33). See remarks for Entomobrya decemfasciata for more information regarding species diagnosis and delimitation. Also, see Suppl. material 3: A,B for photographs of the type specimen.

Distribution.

Endemic to North America (Suppl. material 2: M). Many records may be misidentifications due to similarity in color pattern and chaetotaxy with Entomobrya decemfasciata . Records of Entomobrya quadrilineata without thoracic stripes are most likely Entomobrya decemfasciata .

Material examined.

USA: Neo-holotype (Christiansen 1951), 1 on slide, Fountain Bluff, Ill. 5-15-32, Coll. Ross + Mohr, INHS Cat. No. 529,188; Neo-paratype (Christiansen 1951), 1 on slide, Fountain Bluff, Ill. 5-15-32, Coll. Ross + Mohr, INHS Cat. No. 529,189; Neo-paratype (Christiansen 1951), 1 in vial, Fountain Bluff, Ill. 5-15-32, Coll. Ross + Mohr; 4 on slides, 13 in vial, Illinois, Monroe Co., Kidd Lake Marsh State Natural Area (37.97211,-89.80135), leaf litter #42, 29.ix.2009 (S. Taylor & F. Soto-Adames), sjt09-114; 1 in vial, Illinois, Pope Co., Bell Smith Springs (37.51882,-88.65782), bare sandstone bedrock above canyon in mosses and lichens, 28.viii.2011 (J. Cech); 1 on slide, Illinois, Vermilion Co., Kennekuk Cove County Park, Windfall Prairie Nature Preserve (40.20995,-87.74181), vacuum hill prairie, 16.vi.2011, AK11-59a; 1 in vial, Illinois, Wayne Co., County Road 580N (38.34122,-88.23992), leaf litter from north side of road, 15.vii.2011 (A. Katz & F. Soto-Adames), AK11-61; 4 in vial, Illinois, Wayne Co. (38.32500,-88.25016), 15.vii.2011 (A. Katz & F. Soto-Adames), AK11-63; 1 in vial, Tennessee, Stewart Co., Land Between the Lakes National Recreation Area,. 25mi down Neville Bay Rd. (36.60757,-87.93457), leaf litter on forest floor, 31.v.2011, AK11-44; 1 on slide, 2 in vial, Tennessee, Stewart Co., Land Between the Lakes National Recreation Area, Fox Ridge Rd (36.66392,-87.98596), leaf litter, 7.viii.2011, AK11-105.