Entomobrya neotenica Katz & Soto-Adames

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 : 42-43

Taxon classification Animalia Collembola Entomobryidae

Entomobrya neotenica Katz & Soto-Adames sp. n. Figs 2, 16C, 29, 30, 39

Etymology.

This species is named for its apparent neoteny; small size and reduced chaetotaxy.

Type material.

Holotype, ♂, USA: Alabama, Lawrence County, William B. Bankhead National Forest (34.3369,-87.3461), leaf litter, 9.viii.2011, AK11-112.

Paratypes, USA: 1 on slide, 1 in vial, Alabama, Clay Co., Talladega National Forest (33.19723,-86.06325), moist leaf litter, 2.i.12 (A. Katz & M. DuBray), AK12-2; 1 in vial, Alabama, Lawrence Co., William B. Bankhead National Forest (34.3369,-87.3461), leaf litter, 9.viii.2011, AK11-112; 1 on slide, Florida, Taylor Co., Econfina River State Park (30.0656,-83.9107), under bark, 9.viii.2011, AK11-116; 2 on slides, 18 in vial, Illinois, Union Co., Anna, Shawnee National Forest, Rich’s Cave, moist leaf litter under bark on fallen tree, 21.vi.2012 (F. Soto-Adames, S. Taylor & A. Katz); 1 on slide, Tennessee, Stewart Co., Land Between the Lakes National Recreation Area (36.5354,-87.9214), forest floor leaf litter, 3.v.2011, AK-43.

Description.

Body shape and color pattern. Body oval and cylindrical. Length up to 1.15 mm. One primary color form (Fig. 29): white and yellow or orange background with black or dark purple pigments forming two lateral triangles on the sides Abd. 3; triangles sometimes reduced to irregular patches. Additional irregular patches of pigment usually on lateral margins of all segments. A band sometimes present along posterior margin of Th. 2. Abd. 5 with 2 dark spots, sometimes forming irregular triangular shapes. Antennae usually light purple near apex and relatively long. Legs usually white, with small purple patches on apical end of femora.

Head. Apical bulb of 4th antennal segment simple or bilobed. Long differentiated smooth setae on ventral side of 1st antennal segment ≈2 –2.5× short setae. Four prelabral setae finely ciliate, appearing smooth under light microscopy. Ornamentation of the distal margin of the labral papillae with single seta or spine-like projections (Fig. 2). Labial lateral appendage slightly curved, relatively thick, not reaching tip of papilla. Dorsal head chaetotaxy reduced (Fig. 30A), macrosetae An’ 0, An3a2, An3a3, A6, M3i, S’ 0, Ps3, Pi1, Pi2, Pm1, Pm1i, and Pp2 absent; S5i usually present; S4i and S6 usually absent. Eyes G and H smaller than A-F but enlarged; G slightly larger than H. Eye patch with 3 setae.

Thorax. Thoracic chaetotaxy reduced, with relatively few supplementary setae. Th. 2 macrosetae a5, m1, m2, m4, m4p, and m4i present (Fig. 30B); all posterior macrosetae (series P) present. Th. 3 macrosetae a1, a2, a3, a4, a4i, a5, a5e, a6, a6i, m5, m5i, m6, m6e, and m7 present (Fig. 30C). Both thoracic segments with few supplemental macrosetae present in zone Pm (Fig. 30B,C).

Legs. Trochanteral organ with triangular setal pattern and up to 20 setae. Unguis with 4 inner teeth (Fig. 16C). Unguiculus acuminate with small serrations on inner edge.

Abdomen. Abdominal chaetotaxy reduced; no macrosetae variation observed. Abd. 1 with 4 macrosetae; a5, m2, m3, and m4 (Fig. 30D). Abd. 2 with 4 macrosetae: a2, m3, m3e, and m5 (Fig. 30E). Abd. 3 with 3 macrosetae: m3, pm6, and p6 (Fig. 30F). Abd. 4 with 6 inner macrosetae (Fig. 30G). Mucronal teeth subequal; mucronal spine smooth.

Remarks.

Entomobrya neotenica sp. n. can be diagnosed by the presence of two lateral dark triangular shaped or irregular spots on Abd. 3, only 3 setae in eye patch, and the absence of head mesoseta An’ 0 and Abd. 3 macroseta m3ep (see Table 2 for ad ditional diagnostic characters). This species is included in the Entomobrya ligata complex (see remarks for Entomobrya ligata ) and has a unique color pattern and chaetotaxy never before reported in the literature. Entomobrya neotenica sp. n. is exceptionally small compared to most Nearctic Entomobrya . In fact, most individuals were thought to be juvenile forms of Entomobrya ligata prior to the observation of the male genital plate. Entomobrya neotenica sp. n. is very similar to Entomobrya ligata and Entomobrya unifasciata sp. n., but can be separated by characters outlined in Table 6.

Distribution.

Endemic to North America (Suppl. material 2: K)