Plinthisus Stephens sensu Wagner 1964
Creators: name: Sweet, Merrill H.
name: Slater, James A.
Publisher: name: Zenodo
Year: 2004
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Rhyparochromidae
Plinthisus

description: Subgenus Plinthisus Stephens sensu Wagner, 1964
The following three groups fall under the nominate subgenus Plinthisus as defined by Wagner, but they are distinctive and each probably will be worthy of generic rank.
RUDEBECKI SPECIES­GROUP
Included species: Plinthisus (Plinthisus) rudebecki Slater, 1964 (Figs. 9, 18, 29, 39, 62, 80, 81, 100)
As noted by Slater (1964), P. rudebecki is an isolated taxon in the African fauna. It is highly distinctive and forms part of the endemic element in the fauna of the southwest Cape. We place P. rudebecki in the nominate subgenus Plinthisus (Wagner 1963, 1964) based on its elongate pronotum, punctate posterior pronotal lobe and profemur armed with two rows of spines. However P. rudebecki warrants recognition as a separate speciesgroup as shown by its large bucculae and abdominal structure with transverse 5–6 suture.
BRACHYOCCUS SPECIES­GROUP
Included species: Plinthisus (Plinthisus) brachyoccus n. sp., P. (P.) debaroensis Linnavuori, 1989.
Plinthisus (Plinthisus) brachyoccus n. sp.
(Figs. 10, 20, 28, 28 a, 41, 54, 55, 68, 84, 85, 102, 114)
Description. Macropterous male. Elongate, robust. Head and anterior pronotal lobe black to very dark chocolate brown. Tylus, anterior margin of pronotum, entire posterior pronotal lobe and femora bright reddish brown. Scutellum castaneous. Hemelytra strongly contrastingly testaceous. Tibiae, tarsi, labium and antennae yellowish, tinged with light tan. Ventral surface dark brown. Surface shining, but not strongly polished; sparsely clothed with inconspicuous short decumbent hairs, these more dense on head and abdominal venter; antennae with moderately long forward­directed hairs on distal ends of segment 2 & 3 and entire segment 4, a strong seta on inner surface of segment 1. A short (0.06) trichobothriumlike seta on eye and 3 setae on tylus; vertex apparently lacking a pair of trichobotriumlike setae (Fig. 10). Abdominal sternum 3 with cluster of 3 trichobothria, 2 short 1 long on each side of meson of sternum; sternum 4 with 1 trichobothrium on each side of meson, other two normal trichobothria extremely short, difficult to distinguish from body hairs. Trichobothria of abdominal sterna 5, 6, 7 just ventral (entad) and spiracles just dorsal (ectad) of shiny horizontal pseudosuture. Posterior trichobothrial pair on sternum 5 oblique, located on coalescent granulose spots just posterior (0.03) to spiracle and remote (0.15) from posterior margin of segment; trichobothria of sterna 6 and 7 near (0.06) posterior margins of sterna; dorsal trichobothrial hair of posterior pairs on sterna 6 and 7 relatively long (0.25), much longer than ventral trichobothrial hair. Entire exposed dorsal surface prominently punctate; punctures on anterior pronotal lobe large and coarse, nearly as large as those on posterior lobe. Propleura (Fig. 10), and area below shining dorsal margin of meso­ and metapleura (Fig. 20) coarsely punctate­rugulose; acetabula smooth, shining.
Head (Fig. 10) strongly declivent; vertex strongly convex. Tylus nearly attaining distal end of first antennal segment. Tylar sutures incised, converging caudad. Length of tylus 0.17, anterior width 0.12. Juga posteriorly strongly convex, anteriorly moderately tumid, apices subacute, almost attaining apex of tylus, jugal sulcus longer than length of eye. Lorum shining, a short low anterior carina along jugal sulcus. Antenniferous tubercles invisible from above; insertion of antennae below and in front of eyes. Ocelli large, oblong, 0.033 X 0.057, placed close (0.031) to inner margin of eye. Eyes narrow, elliptical, and transverse, of about 80 facets, height of eye (0.25) over twice as great as longitudinal length (0.12), and extending laterad to level of anterior pronotal angle. Bucculae relatively high, height (0.10) a little greater than width of first labial segment (0.092), narrowing posteriorly to become merely ridges at level of eyes, these ridges terminating caudad in an elongate V­shaped point at base of head. Visible head length 0.40, width 0.64; interocular space 0.46.
Pronotum (Fig. 10) convex, slightly higher across anterior than across posterior lobe. Lateral margins sharply carinate, narrowly explanate, forming submarginal pale grooves; margins noticeably sinuate, moderately constricted in region of transverse impression. Width across humeri slightly greater than across anterior lobe; anterior and posterior margins shallowly concave. Pronotal length 0.94, width across anterior lobe 1.18, width across humeri 1.28 (pronotal measurements from male paratype). Scutellum triangular, flat, length 0.78, width 0.82. Corium with lateral margins carinate, gently and evenly arcuate. Midline distance from apex of clavus to apex corium 0.72. Midline distance from apex of corium to apex of abdomen 0.56. Metathoracic scent gland auricle (Fig. 20) simple, produced as a low ledge above pleural surface, apex broadened, tear­drop shaped, and curving caudad; dorsal margin of auricle shining, groove and ventral margin granulose. Scent gland area coarsely granulose, small, covering only ventral (=inner) 1/3 of metepisternum, a narrow fringe extending dorsad along anterior margin of metepisternum nearly to dorsal callosed shining area below corium. Metapleural posterior flange weakly differentiated by depression from metapleuron. Posterior margin of flange nearly straight, dorsal corner rounded. Prosternum (Fig. 10) with anterior collar moderately narrow (length 0.14), delineated by weakly defined sulcus that is continuous with groove below lateral margin of pronotum. Mesosternum carinate anteriorly between forelegs, moderately produced and transversely rugose in lightly excavate area between coxal cavity ridges, median furrow absent; ridges adjacent to coxal cavities not deeply impressed mesally.
Abdomen maximum width 1.43, length 1.72. [Abdominal terga (Fig. 41) 3–7 lightly arched, more sclerotized than 1 and 2, caudal margin of tergum 7 nearly straight, very slightly convex; sternal sutures 3–4 and 4–5 moderately dovetailed, suture 4–5 bent distinctly cephalad at level of trichobothria, (in female, sterna 4–5 free, intersegmental margin slightly bent cephalad at level of trichobothria); spiracle 5 a little closer (0.17) to posterior margin of segment than are other spiracles; spiracle 8 small but present; terga 1 and 2 (Fig. 41) relatively wide (1.08), lightly sclerotized, with lateral margins cleft between terga. Plectrum (Fig. 41) on tergum 1 moderately sclerotized, small, width 0.14, length 0.12, striae 1.7 µ apart. Abdominal tergum 3 longest in middle, very slightly carinate along posterior margin, tergal suture 3–4 curving slightly caudad; tergal sutures 4–5 and 5–6 dovetailed, sutures curving caudad so that tergum 6 on midline is shorter than either tergum 4, 5, or 7. Maximum width of terga (across 2 and 4) 1.08; medial tergal lengths 1–0.20, 2–0.05, 3–0.16, 4–0.39, 5–0.33, 6–0.17, 7–0.28. Scent gland scar widths 3–4: 0.03 (anterior scent gland absent or a single pore), 4–5: 0.15, 5–6: 0.20. Terga 6 and 7 and posterior 1/3 of tergum 5 inflexed and grooved laterad to receive connexivum. Connexivum relatively wide, widest across junction of hypopleurites 5 and 6, narrowed cephalad and caudad. Epipleurites 3–6 relatively wide (0.05); hypopleurites 5–6 juncture oblique, others transverse, epipleurite 6 narrowed caudad; hypopleurite widths 2–0.03, 3– 0.6, 4–0.9, 5–0.11, 6–0.12, 7–0.04; lengths 2–0.07, 3–0.18, 4–0.25, 5–0.36, 6–0.47, 7– 0.37; tergum 7 and sternum 7 internally lightly impressed for reception of segment 8 and genital capsule, two apodemes 0.04 apart on anterior margin of sternum 8. Genital capsule (Figs. 54 & 55) width 0.36, posterior rim nearly transverse, bluntly carinate; dorsal opening large compared to clasper opening, parandria slender, fingerlike; epiproct and paraprocts fused into a ringlike structure open ventrally (Fig. 54); anal sclerites a flaplike structure. Clasper (Fig. 68) straight with small carina under the inner projection; small hairs on tip and three setae on mesal surface of blade. Phallus (Figs. 84 & 85) moderately long with sleeve extending half way up the gonoporal process; wings of reservoir very small on distal part of body near neck; holding sclerites small and slender. Spermatheca (Fig.102) very unusual in lacking basal duct, having only sclerotized distal duct; bulb hemispherical. Valvulae length 0.52].
Profemur (Fig. 114) strongly incrassate, armed below with 2 rows of spines; inner row with 2 or 3 very large spines; metatibia with two rows of 4 and 1 spurs; mesotibia with two rows of 3 and 2 spurs. Labium elongate, extending between metacoxae. Length labial segments: I 0.44, II 0.50, [III 0.42, IV 0.30]. Antennae with segments 2 and 3 distinctly clavate. Length antennal segments: I 0.21, II 0.40, III 0.61, IV 0.40. Total body length 3.80.
Brachypterous form: Coarsely punctate (as in macropter) over entire hemelytron. Clavus and corium fused. Lateral corial margins carinate and evenly and narrowly convex. Apical hemelytral margin strongly angulate, slightly convex, laterally extending over anterior portion of tergum 6 but leaving most of tergum 5 exposed mesally; a distinct membrane remnant present. Length hemelytron 1.54, maximum width 0.72; length hemelytral commissure 0.68. Total body length 3.44.
Material Examined. HOLOTYPE: Macropterous male. CONGO: Lusinga, 1.760 m., Parc Nacional Upemba, 22­23­IV­1949 (Mis. G. F. de Witte 2540a). In Congo National Parks Museum, Brussels.
PARATYPES: CONGO: 1 male (macropter) same data as holotype. 1 female (brachypter) same data as holotype except 15­III­1947. 1 male (brachypter) Lusindoi, 27­VIII­ 1911 (L. Gengeon). In Museu do Afrique Centrale, in J. A. Slater and M. H. Sweet collections.
Etymology. The specific name brachyoccus is derived from the Greek, the prefix brachy­ from brachys, meaning short, and the stem ­occus from okkus, meaning eye, in reference to the greatly foreshortened eyes of this species, which is unique among the Plinthisinae.
Discussion. We place the Brachyoccus Species­Group in the subgenus Plinthisus sensu Wagner (1963, 1964) because the pronotum is relatively long as compared with its width and there are two rows of spines on the male profemur. However, P. brachyoccus differs from other known species of Plinthisus s. s. in having the entire dorsum evenly and coarsely punctate, and is especially distinguished by the narrow foreshortened eyes (Fig. 10), which are unique within the genus Plinthisus. Also unique is the spermatheca (Fig. 102) in which the entire duct is sclerotized, whereas in all other Plinthisinae the duct is divided into a basal unsclerotized and a distal sclerotized duct.
We tentatively include P. debaroensis Linnavuori, 1989 in the Brachyoccus Species­ Group because the entire pronotum is similarly coarsely punctate and the male protibia is only slightly bent (Linnavuori 1989). P. debaroensis differs from P. brachyoccus in having very small eyes (width 1/6 of interocular space) and being much smaller, 2.5 mm in length as compared to 3.4–3.8 mm for P. brachyoccus. Further study may show that these species to belong in separate species­groups.
HIRSUTUS SPECIES­GROUP
Included species: Plinthisus (Plinthisus) hirsutus Slater, 1964. (Figs. 10, 19, 30, 40, 51, 52, 67, 82, 83, 101, 113)
P. hirsutus Slater resembles superficially the subgenus Dasythisus Wagner, 1964 in having long upright hairs, a character Slater (1964) remarked on in comparing P. hirsutus to P. compactus (Uhler). (The Nearctic species Plinthisus compactus (Uhler), P. americanus Van Duzee, and P. indentatus Barber should be placed in the Palearctic subgenus Dasythisus.) However, unlike Dasythisus (Fig. 112), P. hirsutus does not have a large tooth­like spur midway on the male protibia (Fig. 113). Because the male protibia of P. hirsutus is distinctly bowed as in P. brevipennis (Fig. 111), the type species of Plinthisus (s. s.), rather than slightly bent as in Locutius (Fig. 110), and the brachypterous pronotum is relatively long as compared to its width (ratio 1.18) as in Plinthisus (s. s.), rather than relatively short as in Locutius (ratio 1.46), P. hirsutus fits Wagner's concept of the subgenus Plinthisus better than the subgenus Locutius and is therefore provisionally placed in the subgenus Plinthisus, although as indicated above and in the key, P. hirsutus certainly represents a distinct species­group. In support of the uniqueness of P. hirsutus is the unusual double plectrum (pl and spl) in the male abdomen (Fig. 40), which may correspond to the unusually long stridulitrum (Fig. 30), and in proctiger (Fig. 51), the fusion of the epiproct and the paraprocts into a nearly circular structure surrounding a flaplike anal sclerite is unique, as is the sharp posterior lip on the genital capsule rim (Fig. 52).
description: Published as part of Sweet, Merrill H. & Slater, James A., 2004, An analysis of species­groups of the genus Plinthisus Stephens (Hemiptera: Rhyparochromidae) in the Ethiopian Region with the description of eight new species, pp. 1-56 in Zootaxa 533 on pages 8-11, DOI: 10.5281/zenodo.157231