Neodietrichia Özdikmen, 2008

Milne, Marc A., O’Neil, Caylie & Bertaux, James, 2023, A taxonomic revision of Neodietrichia (Araneae: Linyphiidae), a rarely encountered but widespread spider taxon, Zootaxa 5296 (1), pp. 31-44 : 33-35

Neodietrichia Özdikmen, 2008

Neodietrichia Özdikmen, 2008: 537 .

Type species: Dietrichia hesperia Crosby & Bishop, 1933 , by monotypy. Neodietrichia Özdikmen, 2008 replacement name for Dietrichia Crosby & Bishop, 1933 preoccupied in Bivalvia by Dietrichia Reck, 1921 .

Etymology. The original name, Dietrichia , was a patronym in honor of Henry Dietrich, a colleague of Crosby and Bishop at Cornell University ( Cameron 2005). The replacement name, Neodietrichia , literally translates to “New Dietrichia ”.

Diagnosis. Neodietrichia males possess dual cephalic sulci on the sides of the carapace behind the PLE, the most anterior of which leads to a pit and the posterior sulci extend posteriorly from the median part of the anterior sulci and taper distally ( Fig. 1 ). Neodietrichia males may also be distinguished from those of other similar erigonine genera (e.g., Mecynargus and Semljicola ) by the presence of a large, anteriad, scimitar-shaped radical apophysis unlike any other erigonine genus ( Figs. 2B, C , 3A, E , 4B, C , 5A, D ; Crosby and Bishop 1933, fig. 202; Hackman 1954, fig. 55; Marusik et al. 2006, figs. 46 and 79). Moreover, males of Neodietrichia possess a longer tibial apophysis than any of the aforementioned genera, often accompanied by distal teeth ( Figs. 2C–E , 3C, D , 4C–E , 5C, E, F ; Crosby and Bishop 1933, fig. 201 and 203; Hackman 1954, fig. 53–57; Marusik et al. 2006, figs. 45, 47, 81, and 82). Unlike most erigonines, Neodietrichia females possess epigyna with a sclerotized hood (somewhat similar to Masoncus ). Similar to Masoncus , a median lobe exists posterior to the hood. However, unlike Masoncus in which the hood is near the midline of the epigynum ( Chamberlin 1949, figs. 95, 100, 103; Cushing 1995, fig. 5), the hood in Neodietrichia epigyna is anterior to all other epigynal parts ( Figs. 2G, H , 3F, G , 4G, H , 5G, H ). Moreover, the median plate in Neodietrichia epigyna is wider posteriorly and narrows anteriorly ( Figs. 2G, H , 3F, G , 4G, H , 5G, H ) unlike the square-shaped median plate in most Masoncus ( Chamberlin 1949, figs. 95, 103; Cushing 1995, fig. 5).

Description ( Figs. 1–5 ). Medium-sized (1.38–2.83) erigonines with dusky orange to brown cephalothoraxes and gray to black abdomens. Eight eyes ringed in black. AME slightly smaller than the other subequal eyes. Posterior eye row slightly procurved, anterior eye row slightly recurved so that lateral eyes from both rows are touching. Chelicerae with 5 promarginal teeth and 4–5 retromarginal teeth; small mastidion present; cheliceral file with 8–20 ridges. Carapace oval, slightly less than half as wide as long with 2–3 hairs along midline. Males with many hairs on clypeus just below AME, between AME and ALE, between AME and PME, and some behind PME. Males also possess pits and dual elongated sulci on the carapace behind PLE; anterior sulci shallow just behind PLE and deepen as they extend posteriorly, often curving ventrally, to pit; posterior sulci extend posteriorly from median part of anterior sulci and taper distally. As in many erigonine males ( Schaible et al. 1986), pits in Neodietrichia demonstrate the production of a substance that is assumed to be a nuptial gift for mating females (see arrow in Fig. 1 ). When viewed laterally, carapace is slightly concave from PLE to approximately 1/2 to 2/3rds towards posterior end of carapace at which point it declines to pedicel. Carapace dusky orange to brown; sternum slightly longer than wide, pointed posteriorly between coxae of leg IV. Abdomen oval, covered with simple setae, color ranges from light gray to black, sometimes mottled with four points of muscle attachment darker. Venter color and pattern similar to dorsal side. Epiandrous fusules absent; colulus approximately twice as long as wide; anterior spinnerets longer and wider than posterior ones, cone-shaped. Legs slightly lighter than carapace color, concolorous, relative length 4, 1, 2, 3; femur I approximately 3/4 as long as carapace; metatarsi I–III each with a single trichobothrium; metatarsus IV lacking trichobothrium; paired tarsal claws and median claw without teeth. Tibia I–III each with a single trichobothrium; tibia IV with 1–4 trichobothria of varying lengths; trichobothrium on metatarsus I distal (n = 68, min = 0.52, max = 0.85, median = 0.75). TmI (n=67), 0.52–0.85 (mean = 0.74). Tibial macrosetae 2221 (1 distal and 1 proximal on legs I–III) with distal macrosetae on legs I–III greatly reduced. Patellar macrosetae 2222 (1 distal and 1 proximal) with the proximal macrosetae greatly reduced. Male palp simple, possessing a large, anteriad, scimitar-shaped radical apophysis; embolus often curved and directed towards central radical apophysis from retrolateral edge; tegulum with distal protegulum retrolateral to radical apophysis; large prolateral radix; palpal tibial apophysis long, pointed, and occasionally with spines in various arrangements ( Figs. 2B–E , 3A, C–E , 4B–E , 5A, C–F , Crosby and Bishop 1933, fig. 201 and 203; Hackman 1954: figs 53–54 and 56–57; Marusik et al. 2006, figs. 45, 47, 81, and 82). Epigynum ( Figs. 2G, H , 3F, G , 4G, H , 5G, H , Crosby and Bishop 1933, fig. 204) with median plate that widens posteriorly; concave anterior hood either single ( N. hesperia ) or doubled ( N. depressum n. comb.); both spermathecae visible ventrally, present medially, either directed anteriorly, lateral to median plate ( N. depressum n. comb.) or directed centrally, underneath median plate ( N. hesperia ); dual copulatory openings located centrally lateral to median plate.

Distribution. California and British Columbia east to Nova Scotia and south to South Carolina; likely exists throughout North America ( Fig. 7 ).

Natural History. May be found on the trunks, under the bark, or on upper branches (~ 5m) of various species of trees within undisturbed forests with deep leaf litter. Specimens have also been found in the leaf litter of older forests, agricultural fields, in lichen, bird nests, on buildings, and in swamps. There is strong evidence that this species frequently balloons as many examined specimens were captured in malaise traps, flight intercept traps, and Lindgren traps. In fact, one specimen was collected after it ballooned onto the shirt of the wife of a prominent linyphiid-specializing arachnologist (Dr. Michael Draney, U. Wisconsin Green Bay ) .

Figures

FIGURE 1. SEM micrograph of the lateral view of the carapace of Neodietrichia depressum n. comb. (MM 6D15, Indiana, Johnson Co.). Arrow indicates substance filling pit. S, sulci.

FIGURE 2. Photographs of Neodietrichia hesperia (Male: MCZ 140958, Maine: Washington Co.; Female: RB, Ohio: Vinton Co.). A, Male habitus; B, male left palp, ventral view; C, male left palp, prolateral view; D, male left palp, dorsal view; E, male left palp, retrolateral view; F, female habitus; G, epigynum, ventral view; H, epigynum, cleared dorsal view. Scale bars represent 0.25mm.

FIGURE 3. Illustrations of Neodietrichia hesperia (Male: AMNH_IZC 00328051, holotype; Female: RB, Ohio: Vinton Co.). A, Holotype male left palp, ventral view; B, male carapace, lateral view; C, holotype male left palpal tibial apophysis, retrolateral view; D, holotype male left palp, dorsal view; E, holotype male left palpal embolic division, prolateral view; F, epigynum, ventral view; G, epigynum, cleared dorsal view. R, radix; E, embolus; Pt, protegulum; RA, radical apophysis; T, tegulum; Pc, paracymbium; Su, sulci; H, hood; S, spermathecae; CO, copulatory openings; MP, median plate; CD, copulation ducts; FD, fertilization ducts.

FIGURE 4. Photographs of Neodietrichia depressum n. comb. (MM 6D15, Indiana, Johnson Co.). A, Male habitus; B, male left palp, ventral view; C, male left palp, prolateral view; D, male left palp, dorsal view; E, male left palp, retrolateral view; F, female habitus; G, epigynum, ventral view; H, epigynum, cleared dorsal view. Scale bars represent 0.25mm.

FIGURE 5. Illustrations of Neodietrichia depressum n. comb. (MM 6D15, Indiana, Johnson Co.). A, Male left palp, ventral view; B, male carapace, lateral view; C, male left palpal tibial apophysis, retrolateral view; D, male left palpal embolic division, prolateral view; E, male left palpal tibial apophysis, dorsal view; F, same, variation; G, epigynum, ventral view; H, epigynum, cleared dorsal view. R, radix; E, embolus; Pt, protegulum; RA, radical apophysis; T, tegulum; P, paracymbium; TbA, tibial apophysis; Su, sulci; K, keel; H, hood; S, spermathecae; CO, copulatory openings; MP, median plate; CD, copulation ducts; FD, fertilization ducts.

FIGURE 7. All known collection locations of Neodietrichia. Open circles represent Neodietrichia hesperia. Filled circles represent Neodietrichia depressum n. comb.