TAES 142: 215-235 RESEARCH ARTICLE ISSO 0002-8320 http://taes.entomology-aes.org/ The brachypterous ground-litter-inhabiting species of Rhyopsocus Hagen (Psocodea: ‘Psocoptera’: Trogiomorpha: Psoquillidae) from southwestern United States, Mexico, and Guatemala, with descriptions of two new species EDWARD L. MOCKFORD1 1School of Biological Sciences, Illinois State University, Normal, Illinois 61790 – 4120 [email protected] ABSTRACT This work is aimed at the species-level identification of the brachypterous forms of the genus Rhyopsocus found primarily in ground litter throughout southwestern United States, Mexico, and Guatemala. Characters for separation of species used in the present study and in past studies are reviewed critically. A revised definition ofRhyopsocus is given, based in part on venation of macropterous forms. The structure of the complex Rhyopsocus phallosome is compared to that of the species of the genus Psoquilla Hagen. Two new species of Rhyopsocus are described, both from southwestern United States and known to extend into Mexico. The descriptions of Rhyopsocus maculosus García Aldrete, Rhyopsocus micropterus Mockford, Rhyopsocus texanus (Banks) and Rhyopsocus concavus Garca Aldrete are augmented with some new characters. A key to the brachypterous forms of Rhyopsocus species occurring in the area under study is presented. The question of whether the species dealt with here form a clade within Rhyopsocus is briefly discussed but not resolved. Key words. Psocoptera, Rhyopsocus, new species, ground litter, southwestern United States, Mexico, Guatemala. INTRODUCTION The question of whether or not these Rhyopsocus species form a clade within the genus Rhyopsocus Throughout the southwestern borderlands of is discussed but must remain open at present, as the United States, and in much of Mexico and the phylogenetic structure of this genus and of parts of Guatemala, brachypterous psocids of the the entire family Psoquillidae remains poorly genus Rhyopsocus Hagen (1876) are frequent and understood. sometimes abundant in woodland ground litter. Included are four described species: Rhyopsocus MATERIALS AND METHODS texanus (Banks) (1930), Rhyopsocus micropterus Mockford (1971), Rhyopsocus maculosus García The material examined is as follows: R. celtis Aldrete (1984b), and Rhyopsocus concavus García n. sp., 32 adults and 2 nymphs; R. quercus n. sp., 80 Aldrete (1987). Also included are two new species adults and 35 nymphs; R. maculosus, typical form, here named and described: Rhyopsocus celtis n. 8 adults, and 4 nymphs; R. maculosus “form B” sp. and Rhyopsocus quercus n. sp. Color variation (see discussion under that designation), 48 adults in local populations is noted for R. maculosus and and 25 nymphs; R. micropterus, 2 adults; R. texanus R. quercus. A key for the identification of adults of (brachypterous forms), 9 adults. R. concavus , 4 these brachypterous forms is included. Ecological adults. relationships among these species and others in the Procedures and abbreviations are as noted by same guild of small detritivores are considered. Mockford (2011) with the following exceptions. Publication date: 1 November 2016 urn:lsid:zoobank.org:pub:9DAA3BF1-786C-40D1-81FF-8DD6CA539889 216 SOUTHWESTERN RHYOPSOCUS All measurements (except total body lengths) were c) relative curvature of basal pieces of external made on slide-mounted specimens. The image of paramere (Figs. 12, 34); d) ‘pebbled’ vs. smooth a whole specimen was taken with a Nicon Infinity surface of internal paramere (Figs. 12, 34); e) 1 camera mounted on a Nicon NI-150 dissecting relative size of entire radula and nature of its surface microscope. Also, in the Material examined (Figs. 6, 13). sections, “m” and “f” are used to indicate sexes 6) Female external and internal genitalia: of adults, and “ny” is used to indicate nymph or a) nature of the apical valvular sclerite (Figs. nymphs. Holotypes and allotypes will be deposited 22, 35, 39, 42, 44); b) nature of the spermapore in the Illinois Natural History Survey, Champaign, sclerite (Figs. 11, 23, 26, 38, 43); c) nature of the Illinois (INHS). Paratypes will be deposited in spermathecal beak and its platform (Figs. 11, 24, the collection of the author, currently housed in 36, 41). the School of Biological Sciences, Illinois State Other characters that have been used but appear University, Normal, Illinois (ELM), and in the to be of little value include the following: 1) shape insect collection of the Instituto de Biología, of the ovipositor valvulae: this may vary with their UNAM, Mexico City, (IBUNAM). orientation in the preparation; 2) size, shape, and surface features of the spermathecal accessory SYSTEMATICS bodies: these vary in size and shape within a species and may be affected by the mode of preparations of Characters for separation of species of a slide. brachypterous Rhyopsocus. Small psocids that produce neotenic forms, such as these Genus Rhyopsocus Hagen (1876) brachypterous Rhyopsocus species, present difficulties to the taxonomist in that very few Rhyopsocus Hagen, 1876: 55. characters remain for comparison, and comparisons Deipnopsocus Enderlein, 1903: 358. must be done with great care. The following Rhyopsocopsis Pearman, 1929:107. characters have proven useful in the set of species considered here. Revised definition. With the characters of the family Psoquillidae, including a membranous distal 1) Head color (excluding compound eyes): region on the antennal scape, here called “scape head uniformly pale, or with dark regions confined organ” (Fig. 3). Ocelli, when present, close together to ecdysial lines and a band from antennal base to on a triangular field. Compound eyes generally compound eye (Figs. 7, 25), versus dark regions with a single dorsal seta, the ocular seta (Figs. more extensive, affecting the parietal regions of the 7, 25, 40). P2 with a spur sensillum; P4 usually vertex (Fig. 40). slightly swollen distally, resulting in a somewhat 2) Antenna: a) number of flagellomeres; b) hatchet-head shape (Figs. 15, 27); P4 with one or relative size of scape organ (Fig. 3). more thin-walled sensilla, either simple (Figs. 16, 3) Maxillary palpus: a) shape and relative length 28, 37) or bifid (Fig. 8). Lacinial tip with two tines, of P2 spur sensillum (this may prove to be sexually either equal in length or the outer one longer (Fig. dimorphic); b) details of preapical sensilla of P4; c) 9). Antenna with 18 – 21 flagellomeres; a subapical precise shape of P4 (must be used with care because dactyloid sensillum on each of several flagellomeres of variation with position). beyond f5 (Fig. 14). Wings with membranes clear, 4) Length of forewing; comparison to some unmarked. In the forewing, vein Sc in the wing base other body part might be useful but was not done forming a short loop and rejoining vein R + M + here. Cua, often giving off a branch to the wing margin 5) Male external genitalia: a) relative (Fig. 4); pterostigma closed basally, 4 – 5 times as prominence of raised lobes on distal margin of long as its greatest width; cell cua also much longer hypandrium (Figs. 20, 32); b) precise shape of than its greatest width; vein A in the forewing end pieces of external parameres (Figs. 5, 12, 34); distinct, but not always reaching the wing margin. MOCKFORD 217 Legs relatively short; femora slightly swollen; tibiae tip of the phallosome (as it does in Psoquilla) but each with two distal spurs, some forms with a small lies over the paired distal pieces, sometimes with a additional spur. Tarsi 3-segmented; claw (Fig. 10) slender extension distal to them. without a tooth; pulvillus abruptly curved near The ovipositor consists entirely of the paired base, forming a nearly right angle, expanded at tip. valvulae, presumably the third valvulae, throughout Structure of terminal abdominal segments in general family Psoquillidae. In Rhyopsocus, the distal end characteristic of the family. Spermathecal accessory of each valvula includes a more heavily sclerotized bodies spherical or oblong (Fig. 11). strip, here called the apical valvular sclerite (Figs. The genitalic and spermathecal features 22, 35, 39, 42, 44). On its dorsal surface, this of Rhyopsocus. The skeletal structure of the sclerite bears a pair of short setae that arise on phallosome was analyzed for the psoquillid genus somewhat raised, button-like bases, thus they are Psoquilla Hagen by Mockford and García Aldrete here called the button setae. The bases of these two (2010), with a detailed illustration for P. infuscata setae are always included in the apical valvular Badonnel. Phallosomes of the Rhyopsocus species sclerite. dealt with here are very similar to that of P. The spermathecal system (Fig. 11) consists of infuscata. The principal differences are referred the spermathecal sac, structures on a small flattened to here by the numbers (see also Fig. 5) used by or slightly depressed area on the posterior end of Mockford and García Aldrete (2010, Fig. 1 and the sac, the sperm duct and its distal opening called note). Structure #2, inner portion of external the spermapore, which is surrounded by a small paramere, extends to the tip of the phallosome and sclerite, the spermapore sclerite. In Rhyopsocus, is completely fused with structure #1, the outer the surface of the spermathecal sac is membranous cowl of the external paramere, in its distal half. with its walls somewhat reinforced with scattered The endophallic distal piece of each side, structure sclerotic rings. The structures on the posterior end #4, which takes on the appearance of a loon’s head of the sac consist of the beak and its platform, a in lateral view (Figs. 5, 12, 34), is attached to the pair of accessory bodies and their ducts, and the major apodeme, structure #3, near the distal end sperm duct. The beak is a paddle-shaped sclerotic of the apodeme. The “loon’s head” organ contains appendage seated on a small sclerotic platform. It a dark mass of either granular material or tiny receives the sperm duct at its base. The accessory denticles, here called the dark organ (Figs.