Geelus, Stiller, 2020

Stiller, Michael, 2020, A new leafhopper genus Geelus and 12 new species (Hemiptera, Cicadellidae Deltocephalinae) from Southern Africa, Zootaxa 4786 (3), pp. 301-344 : 303-306

Genus Geelus gen.n.

Type species: Geelus dundraad gen. n. & sp. n., by present designation.

Type locality: South Africa, Western Cape Province, Wiedouw Farm at the base of Gifberg Pass, near Vanrhynsdorp , -31.7334, 18.7666 .

Diagnosis. Male and female macropterous with hind wing with articulated jugal lobe, 4.2–5.4 mm from apex of crown to apex of tegmina. Face roundly merged with crown. Crown uniformly rounded with medial length similar to length next to compound eye, or acute. Yellowish to stramineous without fuscous markings or sometimes with light brown to brown circular markings on crown and pronotum (e.g. G. dundraad from Klipheuwel, the road between Koelenhof and Klapmuts and Studland farm, Muldersvlei), and sometimes markings in tegmina. Pygofer lobe dorsomedially with ventrally or dorsoposteriorly curved spine-like process or apically with dorsomedially or mediodorsally curved spine-like process. Plate with uniseriate macrosetae. Connective Y-shaped with stem slightly shorter than arms. Style with preapical lobe narrow or absent.Aedeagus with shaft thin or thick, tubular or depressed dorsoventrally, immaculate or dentate apically, subapically on anterior surface or medially, with process shorter than diameter of shaft.

Etymology. Named for the yellow color of its species in Afrikaans, the language mostly spoken in the Western Cape Province of South Africa, geel, pronounced, according to the International Phonetic Alphabet /xeəl/, /ɣeɫ/. Latinized by the suffix -us, gender masculine.

Male, female & nymph. Color. Most species entirely yellow to light brown, without markings (e.g. Figs 1 A–D, 1G, 1H, 2A, 2H, 5H) except specimens of G. dundraad from Koelenhof—Klapmuts road, Klipheuwel and Studland farm, Muldersvlei area, with four distinct and two less distinct brown spots on the crown and 2–4 brown spots on the pronotum ( Figs 1E, 1F , 2E, 2F ). Geelus haakdraad with many brown to dark brown irrorations and patterns in claval cells ( Figs 15C, D, H, I ) or some specimens of G. haakdraad yellowish ( Figs 15A, B, E, F ). Scutellum yellow to light brown, basal angles usually as rest of scutellum. Tegmina with cells translucent, veins yellow to light brown, hind wings smoky translucent, giving tegmina darker appearance. Nymphs uniformly light brown to yellow, typical of adult color. Some specimens with distinct median pale yellow, longitudinal line and some specimens with small paired, dark brown marking at margin of face and crown ( Figs 5D, 5G , 7G, 7H ). Small nymph, considered early instars, were rare, 2.0– 2.5 mm long with color as in Figs 5B, C . Large nymphs considered late instars were 2.8–3.9 mm long.

External morphology. Head in dorsal view with crown uniformly rounded or triangular in Geelus haakdraad , apical angle obtuse (trigonometric value, all species, both sexes, 122.4 °±5.3°, n=583), smallest angle in some specimens of G. haakdraad , 110°, largest angle in some specimens of G. dundraad , 136°; crown rounded to face, ocelli on margin of crown, 66.2–87.1µm between ocellus and eye; disc smooth. Pronotum transversely rugose ( Fig. 3A ), with short, lateral carina ( Fig. 3C ). Face with clypellus constricted at base, clypeus with margins divergent ( Fig. 3B ). Nymph with equidistantly triangular crown (e.g. Figs. 2 B–D, 5B–D).

Chaetotaxy. Setal arrangement for metafemur distally 2+2+1, with median pair unequal in length, single, basal seta longer than distal pairs of setae. Metatarsomere I distal plantar surface with four rounded platellae and one acute seta, metatarsomere II distally with 2–3 rounded platellae, and lateral setae both acute or one acute seta. Setal arrangement for protibia 4+4 and mesotibia 4+1. Profemur with 10–15 short AV setae, intercalary setae approximately 10 and one thicker and longer AM seta distally.

Wings. Tegmina with four apical cells, 2–3 anteapical cells (inner anteapical and inner discal cells sometimes merged), appendix very narrow. Hind wing with jugal lobe.

Male & female. Abdominal apodemes. Posterior apodeme with medial, paired desclerotized lobes, lobes elongated mediad or narrow, shape rounded or angulate, lobes often larger than in female. Anterior abdominal apodeme with narrow desclerotized paired lobes.

Male. Size. Average range for all species. Length from apex of crown to apex of tegmina 4.21–5.25 mm. Crown median length 0.36–0.43 mm. Crown length next to eye 0.31–0.35 mm. Pronotum length 0.46–0.54 mm. Head width across eyes 1.32–1.49 mm. Pronotum width 1.25–1.40 mm. Ocellus diameter 38.7–51.2 µm; interocular distance 63.7–84.3 µm (between compound eye and ocellus).

Genital capsule. Pygofer. Dimensions variable, in lateral view, about as long as wide, sometimes longer than wide, slightly compressed dorsoventrally, anterior apodeme usually short, widely attached to pygofer, sometimes elongate. Pygofer medially with sclerotized, paired disk-like structure in phragma, between anal tube and dorsal apodeme of aedeagus, shape ovoid, circular or amorphous, variable in size, orientation vertical or horizontal or intermediate.

Pygofer lobe. Usually widely attached to pygofer, broadly or narrowly triangular; apex broadly or rarely narrowly rounded, up to 30 elongate macrosetae; large, well-sclerotized spine-like process at apex, subapex or base, process curvature convex, concave or sublinear, orientation of apex mediad, ventrad or rarely posteriad, process originating apically, subapically or basally from medial surface of lobe; process sometimes modified, i.e. base with 2–4 short teeth ( G. dundraad , G. driehoekdraad ), apex bipinnate ( G. haakdraad ) or subbase dorsally with numerous denticles ( G. kinkeldraad ).

Anal tube. With segment X conical or cylindrical; anal tube longer, shorter or sometimes as long as pygofer lobe; incision into pygofer deep, more than half way; moderately sclerotized, similar degree of sclerotization as pygofer. Species with short aedeagus usually with membranous recess ventromedially, to accommodate apex of aedeagus. G. viertanddraad with subbasal ventral elongated, rounded process; all other species with base not modified.

Valve. With four shapes recognized: reniform (distal margin rounded, proximal margin concave), lenticular (biconvex margins distally and proximally, symmetric or asymmetric, i.e. curvature similar or different), obtusely triangular (distal margins more or less straight with distal apical angle> 90° and proximal margin straight) and acutely triangular (distal margins more or less straight with distal apical angle <90° and proximal margin straight).

Subgenital plate. Triangular or rectangular; macrosetae usually uniseriate, 4–7 uniseriate, submarginal, fine setae laterally (plates separated by 6–20°) or 12–19 irregularly arranged setae (plates contiguous) or rarely multiseriate, marginal to submarginal, with 20–30 macrosetae ( G. haakdraad and G. viertanddraaad ).

Style. Linear, extending deep into plate (at least half way or further), apophysis denticulate ventrally with apical (e.g. G. slangdraad ), or medial ventral tooth, tooth sometimes visible as lateral protrusion in dorsal profile, or glabrous; apophysis linear to sublinear, curvate in some specimens of G. dundraad , and angulate in G. lemdraad ; apex usually rounded or rarely rectangular or expanded; preapical lobe present or absent; median anterior arm short; lateral anterior arm wide, elongate.

Connective. Stem slightly shorter than arms (stem length/arm length 0.74±0.20), arms subparallel; stem about half as wide as greatest width across arms (stem width/arm width 0.51±0.13). Angle of arms at base 54.2°±9.6°, apices of arms subparallel.

Aedeagus. Two configurations recognized: differentiated into dorsal apodeme with elongate shaft, and short preatrium articulated with the connective or dorsal apodeme reduced with short shaft and elongate preatrium articulated with the connective. Dorsal apodeme right-angled or acutely angled to shaft or dorsal apodeme reduced with atrium and preatrium then obtuse or linear relative to shaft. Shaft thin or thick: thin, 7–30 µm in dorsal or ventral view at apex or subapex, and 11–45 µm in dorsal or ventral view at base or subbase; thick, 50–80 µm in lateral view at apex or subapex, 60–80 µm in lateral view at base or subbase. Aedeagal shaft smooth or with teeth in various combinations and teeth always shorter than diameter of shaft. Shaft tubular, elongate, sometimes compressed or depressed, or short in G. stompdraad ; edentate in G. dundraad , G. platdraad and G. slangdraad , or dentate with subapical and medial unpaired teeth ( G. stompdraad ) or paired, medial teeth ( G. nektanddraad ) or apical teeth ( G. vurkdraad , G. driehoekdraad and G. kinkeldraad ) or subapical teeth ( G drietanddraad and G. haakdraad ).

Female. Size. Average range for all species. Length from apex of crown to apex of tegmina 4.23–5.41 mm. Crown median length 0.39–0.45 mm. Crown length next to eye 0.33–0.37 mm. Pronotum median length 0.49–0.57 mm. Head width across eyes 1.40–1.57 mm. Pronotum width 1.33–1.48 mm. Ocellus diameter 37.5–53.6 μm; in- terocular distance 69.2–89.5 µm.

Genital capsule. Sternite 7 variable, deep or shallow notch with or without long or short rounded, rectangular or notched ligula.

Sternite 7 notched:

Valvula 1. Lanceolate with striate sculpture.

Valvula 2. Narrow, parallel–sided, rounded serrations (sometimes with microserration in trough) on apical third, with shallow dent medially, basal half with sclerotized area.

Valvula 3. With apex wide, base narrow (wide in G. slangdraad ), apex with 3–16 long apical, submarginal macrosetae (length 34–57 µm, range for all species), short macrosetae 17–28µm in length.

Remarks. The genus is placed in Bonaspeiini under Deltocephalinae based on the face smoothly rounded to the crown (carina absent) and the Y-shaped connective with short stem and arms about twice as long as stem. These relationships have been discussed by Linnavuori & Al-Ne’Amy (1983) and Zahniser and Dietrich (2013). The Bonaspeiini genera Capeolix Linnavuori and Renosteria Theron (Deltocephalinae) are probably the most similar to Geelus with regard to wing development, shape and size. Capeolix , with redescription in Davies & Geertsema (1998), is recognized by the brown markings on the face, crown and pronotum, with a distinct marginal transverse marking from the eye to apex of the crown and length from apex of crown to apex of tegmina 4.91–5.23 mm. Genitalia of Capeolix have the pygofer lobe with a short, sclerotized process apically, directed posteriorly and the aedeagal shaft apically or subapically with prominent, elongate, laterally, ventrally or dorsally directed spines. In the present understanding of the generic definition of Capeolix the pygofer process is apical and posteriad. Distinguishing features for Capeolix include the aedeagus with apical, elongate processes (longer than twice the diameter of the shaft); pygofer process apical or subapical and produced beyond apex of pygofer lobe, posteriad or ventroposteriad. In Geelus the pygofer process is apical, subapical or basal, oriented ventrad or mediad with the apex acuminate, and about twice as long as in Capeolix . Other distinguishing features for Geelus are the pygofer process confined to or within the margins of the pygofer lobe; aedeagus with short apical, subapical or medial teeth or processes shorter than diameter of shaft; crown unmarked; and habitus color yellow to light brown. A number of undescribed species allied to Capeolix have been examined and correspond with this definition (M. Stiller, personal observation). Renosteria Theron is distinguished from Geelus by the following features: color yellow-green, size smaller (3.3–4.6 mm), crown pointed and unmarked (ratio of crown length to length next to eye 1.5; crown angle by trigonometry 103.0°±1.8°, 101.1°–104.8°), aedeagus with elongate, paired preatrial appendage, half as long as shaft or as long as shaft. In most species of Geelus the ratio of crown length to length next to eye is 1.2, in G. haakdraad 1.4, internally male genitalia are also distinctly different (see Theron, 1984). Renosteria is also one of the few known host-specific genera occurring in the Fynbos on a pioneer plant, Dicerothamnus rhinocerotis Less. (Asteraceae) . Speciose genera such as Bonaspeia Linnavuori , Caffrolix Linnavuori and Curvostylus Linnavuori need to be re-evaluated based on re-examination of the pygofer process (M. Stiller, personal observation). Davies (1987) and Theron (1974) indicated all species of Bonaspeia with a subapical or medial straight or sometimes curvate pygofer process, and possibly always with a single triangular apical tooth. Species in Caffrolix and Curvostylus either lack the process or have the pygofer process variable in size and orientation. At present the shape of the apophysis of the style appears to be the only means of separation of species in Bonaspeia and Curvostylus . Furthermore, properties of the connective and style require investigation for relations in morphometrics or other features. Stellena nigrifrons (Naudé) ( Theron 1973) has a similar yellow coloration to that of Geelus , but is assigned to the Macrostelini and has a dark brown marking on the clypeus. In contrast Geelus has no prominent fuscous markings (except faint, amorphous markings in the Koelenhof, Klapmuts and Muldersvlei specimens of G. dundraad , and some specimens of two species of Geelus from Namibia ), and the pygofer lobe has a sclerotized process originating apically or subapically, with the apex curved medially with apices overlapping or touching, or ventroposteriorly or ventrally. The aedeagal configuration of Geelus is variable with an unmodified thin or thick shaft, or modified with short apical, subapical or medial spines, directed ventrally or anteroventrally.

Wing development. The new species in Geelus have well developed hind wings, with a jugal lobe, and well developed tegmina. Cerus and Renosteria species have well developed tegmina and hind wings with jugal lobe, albeit narrower than tegmina in the former and wider in the latter. Capeolix , Dagama , Discolopeus , Houtbayana , Korana have well developed fore and hind wings. Provisionally two groups with reduced hind wings are recognized in Bonaspeiini. Narrowed hind wing, about as long as tegmina, without jugal lobe, or reduced jugal lobe: Bonaspeia , Caffrolix , Colistra , Curvostylus , Gcaleka , Kaapia , Kimbella , Megaulon , Proekes , Proekoides , Refrolix . Reduced, scale-like hind wing, tegmina reduced with its apex extending to abdominal tergite 3–5: Basutoia , Bloemia, Bretega , Hadroca , Johanus , Salsocolila , Salsolibia , Tzitzikamaia .

Plant associations. A relatively large number of associated plants have been recorded for many species of Geelus , mostly from Biesiesfontein, Wiedouw and Gifberg Pass (all plants in Table 1). Specimens of G. platdraad collected by Theron at one locality on two different plants produced males with some variation and distinct differences in the shape of the female sternite 7. Geelus dundraad was collected on Rooibos Tea ( Aspalathus linearis , Fabaceae ) in August and November 1996 in commercial and wild habitats, with nymphs in low numbers (31 males, 4 females and 2 nymphs without associated adults from Oudam farm, -32.0733 18.6967, 26.xi.1996, R.G. Oberprieler, R. Stals & M. Stiller, on Aspalathus linearis in 5–6 year old plantation). Geelus dundraad from Gifberg, Biesiesfontein and Wiedouw produced 12 plant records. Records of adults and nymphs with associated plants relative

to total records was still relatively low, e.g. 24 records with nymphs (135 males, 93 females, 201 nymphs, n=429)

that included the following:

1. Geelus dundraad on Diosma hirsuta ( Fig. 22F ), Passerina truncata subsp. truncata ( Fig. 22G ), Phylica oleifolia and Wiborgia mucronata ( Fig. 22H ).

2. Geelus vurkdraad on Calobota angustifolia ( Fig. 22B ) and Oedera genistifolia ( Fig. 22A ).

3. Geelus kinkeldraad on Montinia caryophyllacea ( Fig. 22C ), Pteronia divariculata ( Fig. 22D ) and Searsia undulata ( Fig. 22E ). ( Figs 22 A–H, www.newposa.sanbi.org/sanbi/explore, last accessed August 2019).

Distributions of these and other plants were often much wider than the distributions of Geelus species. Records of adults without nymphs were 66 (301 males, 184 females, n=485) out of 90 in total.

Distribution. This genus was recorded in the Albany Thicket, Fynbos and Succulent Karoo Biomes of the Western Cape and Northern Cape Provinces ( South Africa), with its northern and eastern range still poorly known. The species from Namibia , on the Brandberg and Waterberg Plateau ( G. haakdraad ) and the species from Kamanjab ( G. viertanddraad ) indicated a wider northern distribution.According to Mucina & Rutherford the Succulent Karoo Biome extends further east, but this eastern extent might be dominated by Discolopeus ( Stiller 2019) . Modelling of potential natural distribution is in Figs 23A and 23B suggested a small region despite the well-developed wings and expected higher mobility and wider plant distributions.

Discussion. This genus is described for 12 new species one of which is associated with Rooibos tea in most of the cultivated areas, but has, to date, not been found on the cultivated tea on the coastal plain. Species recognition is difficult due to uniformity of color and shape and their relation with many new species and genera still requiring description. Five specimens were examined representing 2–3 additional species, but will not be described due to low numbers. The trigonometric calculation of the apical angle of the crown appeared more suited than the graphical determination of this angle in an image or line drawing, especially when the margin is rounded in profile. In addition to the angles provided for each species of Geelus , the angles for species of Discolopeus are provided in Table 2 below.

Figures

FIGURE 1. Geelus dundraad gen.n. & sp.n., habitus, dorsally. A. Male, Uitsig, Rooibos Tea; B. Female, Groenkol, Rooibos Tea; C. Male, Jamaka, on Aspalathus; D. Female, Jamaka, Aspalathus; E. Male, Koelenhof specimen; F. Female, Klipheuwel; G. Male, Wiedouw specimen, on Diosma; H. Male, Citrusdal.

FIGURE 2. Geelus dundraad gen.n. & sp.n., habitus, dorsally. A. Male, Brakwater; B. Nymph, Wiedouw specimen, Passerina; C. Nymph, Wiedouw specimen, Passerina; D. Nymph, Oudam, Rooibos Tea; E. Male, Muldersvlei specimen; F. Male, Muldersvlei specimen; G. Female, Muldersvlei specimen; H. Female, Muldersvlei specimen.

FIGURE 3. Geelus dundraad gen.n. & sp.n., male head, wings and genitalia, line drawings. A. Head, dorsally. B. Face; C. Head, laterally; D. Tegmina; E. Hind wing; F. Aedeagus, ventrally; G. Aedeagus, laterally; H. Connective; I. Abdominal apodemes; J. Style; K. Subgenital plate; L. Genital capsule, dorsally; M. Style, apophysis, laterally; N. Style, apophysis, dorsally; O. Genital capsule, laterally.

FIGURE 5. Geelus kinkeldraad gen.n. & sp.n., adult and nymph from Biesiesfontein, habitus, dorsally. A. Male, on Zygophyllum; B. Nymph, on Pteronia, early instar; C. Nymph, on Pteronia, early instar; D. Nymph, on Pteronia, late instar; E. Female, on Pteronia; F. Nymph, on Zygophyllum, late instar; G. Nymph, on Zygophyllum, late instar; H. Nymph, on Antizoma, late instar.

FIGURE 7. Geelus gen.n. species, adult and nymph, habitus, dorsally. A. Geelus vurkdraad sp.n., male, on Calobota; B. Geelus vurkdraad sp.n., female, on Calobota; C. Indeterminable species, nymph, on Calobota; D. Geelus nektanddraad sp.n., male, Biesiesfontein specimen, on Gorteria; E. Geelus nektanddraad sp.n., male, Biesiesfontein specimen, on Galenia; F. Geelus nektanddraad sp.n., female, Biesiesfontein specimen; G. Geelus nektanddraad sp.n., nymph, early instar, on Galenia; H. Geelus nektanddraad sp.n., nymph, late instar, on Gorteria.

FIGURE 15. Geelus haakdraad gen.n. & sp.n., male and female, habitus views.A. Male, Brandberg, dorsally; B. Male, Brandberg, dorsally; C. Male, Waterberg, dorsally; D. Female, Waterberg, dorsally; E. Male, Brandberg, laterally; F. Male, Brandberg, laterally; G. Female, Brandberg, laterally; H. Female, Waterberg, laterally; I. Female, Waterberg, laterally; J. Nymph, Brandberg, early instar; K. Nymph, Brandberg, late instar, on Galenia; L. Face, Brandberg, immaculate, on Galenia; M. Face, Waterberg, marked.

FIGURE 22. Plant distribution maps with associated adults and nymphs of Geelus gen.n. species. A. Oedera genistifolia; B. Calobota angustifolia, Geelus vurkdraad sp.n.; C. Montinia caryophyllacea; D. Pteronia divariculata; E. Searsia undulata, Geelus kinkeldraad sp.n.; F. Diosma hirsuta; G. Passerina truncata subsp. truncata; H. Wiborgia mucronata, Geelus dundraad sp.n.

FIGURE 23. Modelled distributions and plots of Geelus gen.n. species. A. Potential natural distribution, Geelus dundraad sp.n.; B. Potential natural distribution, all species of Geelus; C. Plotted distribution of species of Geelus in South Africa.