Adamawa region is one of the ten administrative regions of Cameroon. It is situated between 6°4959N latitude and 13°150E longitude, altitude level is situated between 1000-2000 m. The climate of this region is tropical soudanian type with two main seasons: dry and rainy season. The temperature is rather fresh at the average of 22°C, rainfall is between 900-1500 mm water/year1. The type of vegetation of Adamawa Plateau is Savanna Guinean constituted of shrub and herbaceous2. These shrubs are found in the Guinean and Soudanian Savanna. The flowering plants are dominated by Annonaceae, Celastraceae, Clusiaceae, Combretaceae, Fabaceae, Flacourtiaceae, Loganiaceae, Meliaceae, Moraceae, Rubiaceae, Rutaceae, Tiliaceae, Verbenaceae and others families. Tiliaceae plant family is also quite represented in the Adamawa region of Cameroon and Grewia venusta can be considered as one of the important plant found in this area. G. venusta wide spread from Senegal to Burkina and Togo, its scattered not much common and never plentiful3. Barks, root and leaves are used in African traditional medicine to fight against diarrhoea, cough, sore injury, backache and sexual infections4.
Psyllids or jumping plant-lice (Hemiptera: Psylloidea) are phloem-feeding insects, mostly associated with angiosperms. Psyllids are poorly studied in terms of taxonomy with about 4000 described species, which probably is less than half of the total number in the world5. Despite the fact that psyllids are most species-rich in the tropics and South temperate regions, the Palaearctic fauna remains the best studied with around 400 species reported from Europe or around 1000 species from China6-8. Very few taxonomic researches on psyllid are reported from tropical Africa9-12. The biodiversity of psyllids in Cameroon was studied by several authors: Tamesse13, Dzokou14 in the West region, Yana15 in the Centre region, Ndankeu16 in the South region and Djakbe and Lebel17 in the Adamawa region. More recently, new psyllid species were described from Cameroon psyllid fauna18-22. More specimens need to be described within the Cameroon psyllid fauna.
The taxonomy of psyllid, revised by Burckhardt and Ouvrard23 indicated that this group comprised eight families: Psyllidae, Triozidae, Phacopteronidae, Liviidae, Homotomidae, Carsidaridae, Calophyidae, Aphalaridae. The Liviidae family included Euphylleurinae and Liviinae subfamily. The Liviinae subfamily included these genera: Diclidophlebia Crawford, Aphorma Hodkinson, Camarotoscena Haupt, Livia Latreille, Paurocephala Crawford and Syntomoza Enderlein. Diclidophlebia genus comprises 25 described species in the world fauna of psyllids24. Sixteen species are African members of pantropical genus Diclidophlebia. From Cameroon, five species of Diclidophlebia genus described are associated with Sterculiaceae (D. harrisoni 25 and D. eastopi 26 on Triplochiton scleroxylon, D. leptonychiae11 on Leptonychia macrantha; Euphorbiaceae D. xuani Messi et al.27; Simaroubaceae/Irvingiaceae D. irvingiae11 on Irvingia gabonensis and Desbordesia glaucescens) (Rutales). The number of unknown psyllids species within the Diclidophlebia genus could be more important in the tropic in general and Cameroon in particular. More surveys in Cameroon are necessary to complete the biodiversity of psyllids. During surveys in the Adamawa region of Cameroon, a psyllid species of Diclidophlebia genus was collected on Grewia venusta Fresen (Tiliaceae). Among African species members of pantropical genus Diclidophlebia, D. pilosa is a single species belonging to Tiliaceae host plant family (Grewia bicolor from Tanzania and Kenya)11. This paper report for the first time, from Cameroon on the description of a new psyllid species feed on a Tiliaceae plant family.
MATERIALS AND METHODS
Type locality: Ngaoundere, Falaise Wack, 7°33053N, 13°33232E, 1375 m.
Holotype: ♀, Falaise Wack, 7 July, 2014. Paratype: Falaise Wack: 6 ♀♀ 4 ♂♂, same date as holotype and 2 fifth instar larvae; 4 ♀♀ 2 ♂♂ and 1 fifth instar larvae, 11 July 2015; Mbé: 5 ♀♀ 1 ♂ and 1 fifth instar larvae, 7°5137,4N; 13°3556,5E; 616 m, 13 July 2015; Tchabal: 4 ♀♀ 1 ♂ and 2 fifth instar larvae, 7°3245,9N; 13°3349,0E; 1365 m, 8 July, 2015.
Type series deposit: The type series of Diclidophlebia andjigae sp.n (Fig. 1a) were deposited in the collections of the Laboratory of Zoology, Higher Teachers Training College, University of Yaounde I, Cameroon (LZUY).
Field survey: The observations and survey took place in various localities of the Adamawa region, Cameroon, from August, 2014-July, 2015. During each survey, host plants were inspected. Adults of psyllid were captured with a mouth aspirator. Nymphs were sampled directly from buds and leaves of the host plant. The host plant was identified at the National Herbarium at Yaoundé (Cameroon) and was deposited in LZUY.
Observations and illustrations: The specimens were preserved dry and slide-mounted or in 70% ethanol and are deposited in Laboratory of Zoology, University of Yaoundé I.
Diclidophlebia andjigae sp.n. psyllid of Grewia venusta of (a) Male adult and (b) Female adult
The morphology was illustrated using transmission Leica microscope and measurements were made from slide-mounted using Leica stereomicroscope.
Terminologies: The terminologies used for the description follow the identification keys of Burckhardt et al.11,28,29.
Head: Vertex, median suture, general cones, ocellus, compound eye; Antenna: Rhinaria, flagellomere; Wing: costal beak, pterostigma, vein, spinules, cells; Leg: metacoxa, meracanthus, metatibia, spurs, arolium; Male genitalia: proctiger, paramere aedeagus, ductus ejaculatorius; Female genitalia: proctiger, subgenital plate, dorsal and ventral valvulae, circumanal ring.
Description of Diclidophlebia andjigae sp.n.
Adult coloration: Brown to dark yellow (Fig. 1). Head and thorax brown, abdomen, excluding genitalia, yellow dark, genitalia brown. Eyes red and ocellous whitish. Antenna yellowish with apices of segments 4-9 and entire segment 10 brown. Forewing transparent yellowish with pattern consisting of brown dots in all cells, excluding apices of cells r1, r2, m1, m2 and cu1. Hindwing transparent yellowish. Legs yellowish, excluding femora with brown pattern consisting of spots.
Structure: Head (Fig. 2a) inclined from longitudinal body-axis, head width 0.72-0.8 mm in males and 0.8-0.92 mm in females. Head width 0.8 times slightly less than body width in males and 0.88-1 mm in females. Vertex sub-rectangular with one fovea on each side of the median suture, vertex surface covered with macro-scopical setae; fronts small and large with long and moderately long simple setae. Fronts bearing the prominent anterior ocellus. Compound eyes globular with two lateral ocelli above of vertex.
Antenna (Fig. 2b) 1.3 times longer than head width with a single subapical rhinarium on each segment 4, 6, 8 and 9; rhinaria with a short sensory setae on basal rim of segment 4, 6 and 8; segment 10 bearing two terminal setae moderately long of which one longer simple et one shorter and truncated. Third antennal segment, 0.16 mm long in both sexes, longer than others segments. Antenna measurements are 1-1.2 mm long in males and females.
Thorax weakly arched; pronotum relatively long, flat and weakly inclined; mesoscutellum swollen and large, metapostnotum with flattened acute tubercle.
Forewing (Fig. 2c) oblong-oval, widest at the middle, more twice times longer than wide. Forewing membrane smooth without setae; spinules present in all cells, covering cells up to veins, excluding c+sc cell which are covering in three quarter length posterior. All veins bearing conspicuous setae; pterostigma moderately wide; vein C+Sc wide, slightly curved, longer than cu1 cell length, ending beyond the middle of vein RS; vein RS strongly curved with apex pointed towards fore margin; veins R and M+Cu1 have sub-equal length; vein M straight; vein M1+2 longer than M3+4; vein Cu1 curved towards hind margin; veins M and RS parallel in the middle part of wing.
Adult organs of Diclidophlebia andjigae sp.n. psyllid of Grewia venusta. (a) Head, (b) Antenna, (c) Forewing, (d) Hindwing, (e) Metathoracic leg, (f) Metatibia apical end, (g) Male terminalia, (h) Male proctiger, (i) Paramere, (j) Aedeagus, (k) Female terminalia and (l) Female proctiger
Scales: a: 2 mm, b: 0.8 mm, c: 0.4 mm, d: 0.2 mm
Forewing measurements are about 1.6 mm long, 0.72-0.8 mm width in males and 2-2.2 mm long, about 1 mm width in females; forewing are 2.1 times longer than width in males and 2.04 times longer than width in females. Hindwing (Fig. 2d) is transparent and shorter than forewing, it measures, venation almost absent, costal and subcostal veins with 2 setae before costal break and 2 grouped 2+5 costal setae after costal beak. Hindwing measurements are 1.2-1.4 mm long, 0.52-0.64 mm width in males and 1.6-2 mm long, 0.6-0.68 mm width in females; hindwing are 2.39 times longer than width in males and 2.78 times longer than width in females.
Metacoxa with large, horn-shaped, sub-rounded meracanthus (Fig. 2e). Metatibia (Fig. 2f) bearing an incomplete crown of 6 sclerotised apical spurs grouped as 4+2 and 4 slender unsclerotised setae; Metatibia length measures 0.48-0.56 mm in males and about 0.6 mm in females. Metabasitarsus without spurs.
Male genitalia (Fig. 2g) with proctiger simple and tubular (Fig. 2h) slightly enlarged, posterior margin rounded, anterior margin straight and apex truncated; proctiger bearing sparse moderately long setosity excluding basal part. Proctiger measurements 0.28-0.4 mm long, it is 0.43 times longer than head width.
Measurements (mm) and ratios of Diclidophlebia andjigae sp.n. adults (N= number of measured specimens)
BL: Body length, BW: Body width, HW: Head width, AL: Antenna length, F1L: Length of first antennal flagellomere, WL: Forewing length, WW: Forewing width, wL: Hindwing length, wW: Hindwing width, MTL: Metatibial length, MFL: Metafemur length, MPL: Male proctiger length, PL: Paramere length, DAL: Length of distal segment of aedeagus, FPL: Female proctiger length, FSPL: Female subgenital plate length
Paramere (Fig. 2i) short and robust, basal and apical parts less wider with margin rounded, anterior margin slightly expanded in the upper part, posterior margin sinuous; outer face with moderately long sparse setae in the basal two thirds, short setae at the apical ends; inner face with two short setae robust at the basal part. Paramere measurements 0.12-0.2 mm, it is 0.21 times longer than head width. Aedeagus (Fig. 2j) 3-segmented with distal portion oblong, medial part narrow, slightly incurved; sclerotised end tube of ductus ejaculatorius long and straight. Aedeagus measurements 0.16-0.24 mm long, it is 0.27 times longer than head width.
Female genitalia (Fig. 2k) short and conical in profile view. Female proctiger (Fig. 2l) pear-shaped, expanded in the middle, apex rounded, circumanal ring cruciform in the dorsal view, proctiger bear several moderately long setae and few long setae (4 in number) at distal ends. Dorsal margin of proctiger sinuous, proctiger measurements 0.48-0.6 mm, it is 0.65 times longer than head width and 1.36 times longer than the subgenital plate. Subgenital plate (Fig. 2k) shorter than proctiger, pointed apically, bearing long sparse setae at the apical part. Subgenital plate measurements 0.4-0.44 mm long. Valvula dorsalis expanded, inner valvula shorter than ventral valvula. Measurements and ratios are found in Table 1.
Fifth instar larvae
Coloration: Light with dark brown spots in dorsal portion of head; wing pad, caudal plate, tarsus, last antennal segments and dorsal sclerite dark brown red eyes.
Structure: Body slightly elongate (Fig. 3a), more than 2.5 times longer than width. Body sparsely covered by minute simple setae on head site, thorax and legs.
Forewing pad (Fig. 3c) with two sectasetae on the external margin. Forewing pad measurements 0.47-0.54 mm width. Abdomen with conical sclerites surrounding spiracles. Caudal plate with three sectasetae surrounding circumanal ring.
Antenna (Fig. 3b) long, 10-segmented with a single subapical rhinarium on each segment 4, 6, 8 and 9.
Fifth larval stage organs of Diclidophlebia andjigae s.n. psyllid of Grewia venusta. (a) Fifth larval stage, (b) Antenna, (c) forewing pad, (d) Caudal plate, dorsal view and (e) Tarsal arolium
Scales bars: a: 2 mm, b: 0.8 mm, c: 0.4 mm, d: 0.2 mm
Measurements (mm) of Diclidophlebia andjigae sp.n. fifth instar larva (N: Number of measured specimens)
BL: Body length, BW: Body width, AL: Antenna length, WL: Forewing-pad length, MTL: Metatibial length
Following number of sectasetae on each segment: 1(0); 2(1); 3(1); 4(2); 5(0); 6(3); 7(0); 8(1); 9(1) and 10(0). Antenna measurements 0.81 mm long.
Anus terminal, circumanal ring consisting of a single row of pores, extra pore fields forming semi-circular bands on dorsal and ventral surface on either side of caudal plate (Fig. 3d). Tarsal arolium (Fig. 3e) triangular, no petiolate, without unguitractor. Fifth larval stage measurements 1.36-1.63 mm long and 0.54-0.63 mm width, it is 2.54 times as long as wide. The measurements are found in Table 2.
Host plant: Grewia venusta, Tiliaceae. Diclidophlebia andjigae sp.n. provokes on its host plant rolling of leaves.
Diclidophlebia andjigae sp.n., psyllids of Grewia venusta differs others pantropical African members of Diclidophlebia genus excluding D. pilosa in forewing characteristic11.
Adults of Diclidophlebia andjigae sp.n., has forewing yellowish with pattern consisting of brown dots in all cells, excluding apices of cells r1, r2, m1, m2 and cu1 It differs from D. xuani with forewing whitish, without pattern of infuscation, veins yellow or light brown, hind margin black basally27. Its also differs from D. harrisoni with forewing whitish with irregular brown patches within cells and apices of the veins25 and also differs from D. eastopi with forewing colouration dark brown which become gradually lighter towards the apex; forewing membrane sometimes consisting with yellowish irregular dots30. Diclidophlebia andjigae sp.n. is closed to D. pilosa, psyllid of Grewia bicolor11 in overalls forewing characteristic; forewing with pattern consisting of brown irregularly spaced dots present in all cells, with conspicuous setae on veins.
Metatibia in Diclidophlebia andjigae sp.n., bears an incomplete crown of 6 sclerotised apical spurs grouped as 4+2 and with 4 slender unsclerotisedsetae. It differs from D. pilosa in the number of sclerotised apical spurs 5+4 and slender unsclerotised setae11. It differs from D. xuani in metatibia with 7-10, irregularly spaced sclerotised apical spurs; outer and inner spurs on raised edges27. Metatibia of D. harrisoni comprised 8 more or less evenly spaced, subequal, weakly sclerotised apical spurs forming a posteriorly open crown25. Metatibia of D. eastopi bears sclerotised apical spurs forming an outer (with 2) and inner (with 3-4) group; outer two spurs on raised, thumb-like process30.
Male proctiger in Diclidophlebia andjigae sp.n., is tubular, slightly enlarged in the middle, posterior margin rounded, anterior margin straight and apex truncated less wider with straight margin. It differs from D. pilosa in the form of with apical margin truncated and not rounded11. Proctiger of D. xuani and D. harrisoni possess a short and thick form25,27. Proctiger of D. dombeya is long, thick, weakly produced posteriorly11. And proctiger of D. eastopi is slender and tubular30.
Male paramere of Diclidophlebia andjigae sp.n., is short and robust, basal and apical parts less wider with margin rounded, anterior margin slightly expanded in the upper part; without sclerotised tooth inward directed. Paramere of D. pilosa without sclerotised tooth inward directed11. Parameres of D. dombeya are long, lamellar, gradually narrowing apically, apex consisting of a strongly sclerotised small tooth directed anteriorly11. Parameres of D. xuani are short, square basally in form, with a weakly twisted, digitiform apical process pointing posteriorly, weakly sclerotised; outer face with moderately long setae along anterior and posterior margins; inner face with long setae27. Paramere of D. harrisoni are short, broad basally, narrowing in apical third, apex consisting of a blunt upwards directed process; outer face with long setae along anterior margin and posterior margin in apical half; inner face with long setae25. Parameres of D. eastopi are short, with a square base in form; outer face bears long setae along anterior margin and apical end; inner face with long setae on basal portion and a few setae on apex of the digitiform process30.
Distal segment of aedeagus of Diclidophlebia andjigae sp.n.: 3-segmented with distal portion oblong medial portion more or less straight, slightly incurved in the middle and narrow end tube of ductus ejaculatorius long and straight and sclerotised. It differs from D. xuani in distal portion of aedeagus tubular in basal half; slightly widened in apical half forming an oval inflation sclerotised end tube of ductus ejaculatorius long and relatively weakly curved27. It differs from D. dombeya in distal segment of aedeagus forming an oblong oval inflation, sclerotised end tube of ductus ejaculatorius relatively short and slightly curved11. It differs from D. harrisoni in distal segment of aedeagus strongly inflated with large ventral hook25. And it also differs from D. eastopi in distal segment of aedeagus strongly inflated with large ventral beak30.
Female proctiger of Diclidophlebia andjigae sp.n.,with dorsal margin sinuous, pear-shaped, expanded in the middle, apex rounded, circumanal ring distinctly cruciform in the dorsal view. It differs from D. xuani in female proctiger which is cuneate, short, dorsal margin strongly concave, apex upturned, pointed27. It differs from D. dombeya in female proctiger with a dorsal margin weakly concave, apex straight, pointed, circumanal ring short, oval11. It differs from D. eastopi in female proctiger which is cuneate and short30.
Female subgenital plate of Diclidophlebia andjigae sp.n., is shorter than proctiger, pointed apically. It differs from D. pilosa where the subgenital plate is rounded in the apical part with few small setae at the margin while it is pointed apically11. It differs from D. harrisoni in female subgenital which is plate, short, pointed apically; circumanal ring cruciform30.
For the fifth instar larvae. Antenna of Diclidophlebia andjigae sp.n. 10-segmented with a single subapical rhinarium on each segment 4, 6, 8 and 9. and following numbers of pointed sectasetae on each segment from 1 to 10: 1(0), 2(1), 3(1), 4(2), 5(0), 6(3), 7(0), 8(1), 9(1) and 10(0). It differs from larvae of D. xuani where antenna is 9-segmented with a rhinarium on each of segments 3, 5, 7 and 8 and following numbers of pointed sectasetae on each segment from 1 to 9: 1 (0), 2 (23), 3 (2 + 2), 4 (0), 5 (2), 6 (1), 7 (2), 8 (0) and 9 (0)27. It differs from larvae of D. dombeya where antenna is 9-segmented and following numbers of pointed sectasetae on each segment from 1 to 9: 1(0), 2(1), 3(2), 4(0), 5(2), 6(0), 7(1), 8(0) and 9(0)11. It differs from larvae of D. harrisoni where antenna is 9-segmented with a rhinarium on each of segments 3, 5, 7 and 8 and following numbers of pointed sectasetae on each segment from 1 to 9: 1 (0), 2 (1), 3 (1 + 2), 4 (0), 5 (2), 6 (0), 7 (1), 8 (0) and 9 (0)25. And it also differs from larvae of D. eastopi where antenna is 9-segmented with a rhinarium on each of segments 3, 5, 7 and 8 and following numbers of pointed sectasetae on each segment from 1 to 9: 1 (0), 2 (1), 3 (1 + 2), 4 (0), 5 (2), 6 (0), 7 (1), 8 (0) and 9 (0)30. Antenna of the last instar larvae of Diclidophlebia andjigae sp.n. are 10-segmented like the one of D. pilosa, its both differs from others Afrotropical species of the same genus with 9-segmented antenna11.
The forewing pad of Diclidophlebia andjigae sp.n. bears two small sectasetae on the external margin. It differs in the number of sectasetae on forewing pad 3-4 in D. pilosa11. It differs from D. dombeya in forewing pad with 3-4 marginal and 8-9 dorsal pointed sectasetae11. It differs from D. harrisoni in forewing pad relatively small with 12-16 marginal pointed sectasetae25. And it also differs from D. eastopi in forewing pad relatively small with 12-16 marginal pointed sectasetae30.
Caudal plate of Diclidophlebia andjigae sp.n. is regularly rounded posteriorly, with three sectasetae on either side of circumanal ring. It differs from D. dombeya in caudal plate large, evenly rounded posteriorly with four pointed sectasetae on the anterior margin, two transverse rows of sparsely spaced pointed sectasetae and two groups of pointed sectasetae near circumanal ring on either side11. It differs from D. harrisoni in caudal plate small, unevenly truncate posteriorly with three pointed sectasetae laterally near the anterior margin on either side and 2+2 pointed sectasetae near circumanal ring25. It differs also from D. eastopi in caudal plate small with three pointed sectasetae laterally near the anterior margin on either side and 2+2 pointed sectasetae near circumanal ring30.
Extra pore fields on caudal plate in Diclidophlebia andjigae sp.n., forming semi-circular bands on dorsal and ventral surface on either side of caudal plate. It differs from D. pilosa in extra pore fields on caudal plate forming an isolated patch dorso-medially in addition to a dorsal and a ventral band11. It differs from D. dombeya in extra pore fields on caudal plate small, consisting of small oval patches11. It differs from D. harrisoni in extra pore fields on caudal plate separated into a dorsal rounded and a ventral angular component, outer band of extra pore field relatively long medially, end pointing outwards25. And also differs from D. eastopi in extra pore fields on caudal plate separated into a dorsal rounded and a ventral angular component; outer band of extra pore field relatively long medially, end pointing outwards30.
Tarsal arolium in Diclidophlebia andjigae sp.n., is triangular, no petiolate, without unguitractor; less longer than claw. It differs from D. pilosa, D. harrisoni and D. eastopi in the length of tarsal arolium about twice as long as claws11,25,30. It differs from D. dombeya in tarsal arolium length about 1.5 times as long as claws11.
The new species, Diclidophlebia andjigae sp.n., psyllid of Grewia venusta, Tiliaceae is described. This study enriched the biodiversity of jumping plant louse of Diclidophlebia genus from Cameroon. The known Diclidophlebia species in Africa is currently seventeen and the number of described psyllid species of this genus from Cameroon is six. It is therefore important to pursue this inventory in order to complete the biodiversity of psyllids in Cameroon in particular and in Africa in general. The taxonomy study of this insect enables us to identify this psyllids. The growers will easily recognize this insect in case of the implementation of an Integrated Pest Management to protect its host plant.
Diclidophlebia andjigae sp.n. is morphological different from others afrotropical psyllids species of the same genus. Specific characters were described on forewing, metatibia bearing an open crown of 6 sclerotised apical spurs, male proctiger with apical ends truncated, paramere without sclerotised tooth inward directed, female terminalia with subgenital plate rounded in the apical part with few small setae surrounding the margin, antenna of the last instar larvae 10-segmented and arolium less longer than claw.
The new species, Diclidophlebia andjigae sp.n., psyllid of Grewia venusta, Tiliaceae is described. This study enriched the biodiversity of jumping plant louse of Diclidophlebia genus from Cameroon. Considering the medicinal importance of the host plant, an integrated pest management against this pest could be necessary in case of domestication of this plant. This identification of the pest could be considered as an important first step of an IPM.
We thank Dr Yana Wenceslas for the preliminary identification of the psyllids species of the collection from Adamawa Region. This research was conducted without any funding source.