The Rediscovery and Probable Phylogenetic Position of Psilopsocus (Psocoptera).
Psyche 68(1):38-44, 1961.
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THE REDISCOVERY AND PROBABLE
PHYLOGENETIC POSITION OF
BY EDWARD L. MOCKFORD
Illinois State Normal University
The genus Psilopsocus has posed a puzzle to students of the Psocop- tera since the time of its discovery. The original description by Enderlein
( 1903 : 305) was based on a single specimen. Although adequate for identification, this description does not permit the genus to be placed beyond suborder in recent classifications. Enderlein placed Ps'ilopsocus in the Mesopsocidae, but gave no reasons for this. Roesler (1g44), apparently without re-examining the type, erected a new family for this genus and placed it in the group Epipsocetae on the basis of similarity of the lacinia in the Epipsocidae and Psilopso- cidae.
It is the purpose of this paper to describe a new species of Psilopsocus from the Philippine Islands, to add to the knowledge of the morph- ology of the genus, and to re-interpret its phylogenetic position. Genus Psilopsocus Enderlein, I 903.
In addition to the characters included by Enderlein in the original description, the following characters are probably important in delimiting this genus :
I. Male phallic sclerotizations in the form of a simple frame with no indication of external parameres (fig. 2.). 2. Ovipositor valvulae complete, i.e. three pairs. 3. Female subgenital plate with a slender central process (fig. I.). 4. Female paraproct with a decided elongation of the posterior margin (fig. 3.).
5. Male paraproct with a pointed apical process on its posterior margin (fig. 8.).
6. Labrum not of the Epipsocus type, lacking a pair of diagonal strap-like sclerites.
The character mentioned by Enderlein of lack of junction of the Psilopsocus nebulosus n. sp. Fig. 1, 9, subgenital plate. Fig.2, 8, hypandri- urn and phallic frame. Fig. 3, 9, left paraproct. Fig. 4, ?, sclerites of 9th abdominal sternite (dorsal view).
Fig. 5, 9, ovipositor valvulae. Fig. 6, 8, lacinial tip. Fig. 7, 8, tarsal claw. Fig. 8, 3, right paraproct. Fig. 9, 8, tip of pedicel (Ped.) and base of first flagellar segment (fl). Ps\che (>8:38-M (1961). hup //psyche einclub orgt68168-038 html
40 Psyche [March
bases of Radius and Media + Cubitus in the hindwing is not found in the species described below, although a fold in the wing membrane running from the Radius just above this junction, to the wing base produces the appearance of two closely parallel veins. In the species described below, the coxal organ is well developed, with both rasp and tympanum. The rasp is composed of tiny in- dentations with raised edges,
Psilopsocus nebulosus, new species
Plate 5 and Text Fig. i
Diagnosis: differs from the generotype, P. nigricornir End., pos- sibly in number of teeth on lacinial tip (6 indicated for nigricornis, 11 in nebulosus), number of ctenidia on basal segment of hind tarsus ( 15 in nigricortlis, 16 to 19 in mebuhsus), shape of the pterostigma (less deep in nebulosus), and details of the forewing markings (text figure I ) , colorless areas being more numerous in nebu/osus, but there being no colorless areas bordering the wing apex in this species. Holotype 8. Measurements (see table I.). Morphology: IO/D (distance between eyes divided by greatest dorsal diameter of eye, method of Badonnel) ^= 0.78, PO (lateral diameter of eye from above divided by greatest dorsal diameter of eye) = 0.94. Apex of Iacinia (fig. 6.) broad, with a distinct lateral and median cusp, the lateral broadest and bearing 10 denticles. Coeloconic sensilla of first flagellar segment two in number, both situated at the extreme base of the segment (fig. 9.). Distinct tarsal ctenidia present only on posterior tarsi, with a row of 17 on Ti and Text figure 1, Pitiopsocus nehulosus n. sp., 6, photomicrograph of right forewing.
19611 Mockford - Psilopsocus 4 1
the rest of the hypandrium and bearing a row of tiny cilia (fig. 2.). Phallic frame (fig. 2.) a simple ring, slightly oblong, rather uniform in width except somewhat thickened apically and for a short distance along each side.
Within the frame are a pair of membranous lobes. Paraproct (fig. 8.) with the usual field of trichobothria extending obliquely downward from its antero-dorsal angle. Posterior margin of the paraproct extended as a lobe tipped with a pointed process. Color (in alcohol) : compound eyes black. General body color dull ivory marked with medium to pale brown. Labrum, antennae, ocellar interval, and terminal two segments of maxillary palpi medium brown. Clypeal striations, cloudy spots around compound eyes and antenna1 bases, and a band bordering epicranial suture pale brown. Thorax irregularly mottled with large pale brown areas including most of the pleura and large areas of the tergal lobes. Brown areas of meso- thoracic tergal lobes darkest at their borders, pale in their centers. Legs dull ivory except medium brown on each coxa, distal end of each femur, distal end of each tibia, and all of each tarsus. Forewing hyaline, marked with extensive pale brown cloudy bands and spots as in text figure I. Abdomen ringed with irregular pale brown cloudy bands. Terminal segments medium brown.
Allotype 9 . Measurements (see table I). Morphology: IO/D = 1.56, PO = 0.72. Tarsal ctenidia present only on posterior tarsi with a row of 18 on TI and one each on T2 and T3. Subgenital plate (fig. I.) with basal pigmented area in the form of two widely diverging arms. Median process of subgenital plate broad basally, abruptly narrowing to a slender tongue about half-way toward its tip; the broad basal portion bearing two large setae and the slender apical portion bearing many setae of various sizes. Sclerites of the 9th abdominal sternite (fig. 4.) in the form Table I.
Length (in mm.) of various characters of Psilopsocus nebulosus
Character 8 8 8 8 9
4.44 4-59 4.65
Hind tibia 1-39 1.43 1 043
Hind tarsus, TI*
0.465 0.440 0.476 0.476
Hind tarsus, T2
0.131 0.131 0.119
* First posterior tarsal segment.
of a transverse ring with three straps' radiating from it and a trans- verse strap basal to it. Ovipositor valvulae (fig. 5.) with first valvula slender; second valvula broad basally, terminating in a long, slender process; third valvula a broad flap bearing many setae. Paraproct (fig. 3.) with field of trichobothria in its antero-dorsal angle. Poste- rior margin of paraproct markedly protruding; ventral and posterior margins bearing many setae.
Variation: aside from variations noted in the descriptions and measurements (table I), four male paratypes have wing and body markings somewhat paler than the holotype male, but this may be due to tenerality. IO/D ratios for three male paratypes are 0.69, 0.70, and 0.70; PO ratios for these are 0.88, 0.85, and 0.91 ; numbers of ctenidia on posterior basal tarsal segment are 16, 19, and 18. Nymph: one nymph taken with adults of P. nebulosus is with little doubt this species. The association is made on the basis of similarity in size, color, (except the distal two-thirds of the abdomen is dark brown in the nymph), and general body shape, also on the structure of the lacinia and tarsal claws. The lacinia is broad apically with several indistinct denticles on the outer cusp. The tarsal claw bears a preapical tooth and a pulvillus of medium width bent at a decided angle near its base, as in the adult (fig. 7.). Type locality : Philippine Islands : Mindanao, east slope of Mt. McKinley, Davao Province, August and September, I 946, in mossy forest, elevation 6400 feet, H. Hoogstraal collector; holotype 8, allotype Q, 4 3 paratypes and one nymph, all in collection of Chicago Natural History Museum.
Discussion : Psilopsocus is apparently very close to the Myopsocidae. The following points of similarity were noted: I. Tarsal structure
a. Number of segments same.
b. Distribution of ctenidia same.
c. Both with preapical tooth on tarsal claw. d. Pulvillus in both of medium width with a decided bend near its point of attachment.
2. Lacinial structure. The lacinial tip of Lichenonzinza sparsa has a broad lateral cusp bearing 13 stubby denticles, and a short median cusp, hence it shows marked similarity to the lacinial tip of Psilopsocus. 3. Male genitalia.
a. Hypandrial margin. The rounded hypandrial margin of Psilopsocus is similar to that of several species of Rhaptoneura, Phlotodes, and Lichenomima.
19611 Mockford - Psilopsocus 43
b. Phallic frame. The simple, rounded phallic frame of Psilopsocus bearing a pair of lateral thickenings and enclosing a pair of membranous lobes is reminiscent of this structure in Lichenominza fiauliani Bad.
(Badonnel, 1955, fig. 529) and Rhaptoneura eatoni McL. ( Badonnel, I 943, fig. I 43) . It differs little from this structure in Lichenomima maxima Sm. (Smithers, 1957, fig. 6). c. Parapi-oct. The paraproct of Psilopscw is similar to those of most Myopsocids in bearing a pointed process on its posterior margin. Although several species of Myopsocids have two such processes, there is only one in Phlotodes mgole~nsis Bad. (Badonnel, 1955, fig. 514). The male paraproct of the latter species resembles that of Psilopsocus in several other respects, including shape of the field of trichobothria and presence of a roughened area antero-dorsad of this field.
4. Female genitalia.
a. Subgenital plate. The subgenital plate of Psilopsocus is sim- ilar in structure to that of Rh~toneura. The resemblance is espe- cially marked in the case of R. africana Bad. (Badonnel, 1955, fig. 508). In both forms the pigmented basal area consists of a pair of widely diverging arms; the central process is broad basally, narrowing abruptly to a slender tongue which bears setae on or near its apex. b. Ovipositor valvulae. Both Psilopsocus and the Myopsocids have three pairs of ovipositor valvulae. The second valvula terminates as a long, slender process in both groups, although this is generally much longer in the Myopsocidae than in Psilopsocus. The third valvula is a simple flap bearing many setae in both groups. c. Sclerites of the ninth abdominal stei-nite. These sclerites in several Lichenomina species (Badonnel, 1955, figs. 522-525; Smithers, 1957, fig. I I) are composed of three main sclerotized areas, and are thus similar in appearance to the same group of sclerites in Psilopsocus nebulosus with their three radiating sclerotized straps. d. Paraproct. The female paraproct is similar in shape, cilia- tion, and position of the field of trichobothria in the two groups. The differences between the Myopsocidae and the Psilopsocidae are not great. The only ones which I have found are (I) presence in Myopsocidae of a connection between areola postica and medial stem in the forewing and absence of this in Psilopsocidae, (2) presence in Psilopsocidae of a spur vein from the pterostigma and its absence in Myopsocidae, and (3) much more complex markings of the forewing in Myopsocidae than in Psilopsocidae, with characteristic alternating dark and light areas on veins in the former group. '
44 Psyche [March
Pearman ( I 936) has designated the families Myopsocidae, Psocidae, and Thyrsophoridae as constituting the group Psocetae. To this group should be added the Psilopsocidae. It appears that this group repre- sents an ancient phylogenetic line within the suborder Psocomorpha, in which the most primitive forms share a broad, multidenticulate lacinial tip with the Group Epipsocetae. It seems likely that this type of lacinial tip, found also in the Amphientomidae (Suborder Trocto- morpha) was present in the earliest forms of the Suborder Psoco- morpha.
I wish to thank the officers of the Chicago Natural History Mu- seum, Mr. Henry Dybas in particular, for arranging the loan of material discussed in this paper. The accompanying photomicrograph (text figure I) was made by Dr. Robert D. Weigel of the Depart- ment of Biological Sciences, Illinois State Normal University. BADONNEL, A. 1943. Faune de France. Psocoptkres. Paris, P. Lechevalier et Fils, 164 pp.
BADONNEL, A. 1955. Psocoptkres de ]'Angola. Comp. Diamant. Angola Pub. Cult. 26 : 1-267.
ENDERLEIN, G. 1903. Die Cope'ognathen des Indo-australischen Faunenge- bietes. Ann. Mus. Hung. 1: 179-344.
PEARMAN, J. V.
The taxonomy of the Psocoptera : preliminary sketch. Proc. R. Ent. SOC. Lond. (B) 5 : 58-62.
ROESLER, R. 1944. Die Gattungen der Copeognathen. Stett. Ent. Zeit. 105: 117-166.
SMITHERS, C. N. 1957. Three new species of Myopsocidae (Psocoptera) from Natal. Proc. R. Ent. Soc. Lond. (B) 26: 11-16.
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