Rhizoecus bolacis, Williams, D. J., 2004

Williams, D. J., 2004, Two new mealybug species from the Falkland Islands (Hemiptera, Sternorrhyncha, Coccoidea, Pseudococcidae), Zootaxa 659, pp. 1-8 : 2-4

Rhizoecus bolacis sp. nov.

( Fig. 1 .)

Description

Body of adult female on microscope slide elongate oval, sides almost parallel, membranous, segmentation distinct, about 1.95 mm long, 0.90 mm wide. Anal lobes poorly developed, each possessing a stout ventral apical seta about 90 µm long and a pair of dorsal setae, each 70–80 µm long, forming a group of 3. Antennae each 210–220 m long, geniculate, with 6 segments; falcate setae, each slightly swollen at tip, on segments 5 and 6; space between antennal bases a little wider than width of a basal segment. Legs well developed; hind trochanter + femur 150–160 m long, hind tibia + tarsus 170–180 m long; claw elongate, about 25 m long; paired claw digitules knobbed, slightly surpassing claw in length. Ratio of lengths of hind tibia + tarsus to hind trochanter + femur 1.06–1.20. Ratio of lengths of hind tibia to tarsus 1.42–1.57. Leg setae slender, except for thick stout setae on inner edge and anterior surface of each tibia and tarsus. Labium 100–110 m long, about 50 µm wide, similar in length to clypeolabral shield. Circulus present, oval, 35 µm wide and 27.5 µm long, nipple­shaped, with rounded medial extension (about 15 µm long and 7.5 µm in diameter at distal end), situated medially near posterior edge of abdominal segment III but within borders of segment. Cephalic plate present, weakly sclerotized, almost quadrate in shape, with a seta present in each corner. Ostioles present, each with inner edges of lips weakly sclerotized, lips of anterior pairs of ostioles each bearing a few short setae and trilocular pores, posterior pair of ostioles with fewer setae and trilocular pores on each lip. Anal ring about 65 µm wide and 50 µm long, situated at apex of abdomen, bearing 6 setae (each 95–100 m long), and 2 rows of cells, these elongate at anterior end of ring, triangular to quadrate towards posterior end of ring. Eyes absent.

Dorsal surface of body with numerous short pointed setae present, many each about 10 µm long, setae absent from intersegmental areas; a few setae each about 30 µm long present across posterior abdominal segments and some setae each about 50 µm long occurring on posterior lateral margins. Multilocular disc pores absent. Trilocular pores evenly distributed in areas occupied by setae. Oral collar tubular ducts present, minute, each narrower than a trilocular pore, sparsely distributed across middle of most segments. Bitubular cerores present, each containing truncate tubes tapering gradually towards distal end and widely diverging, more than half of each tube situated below surface of derm; cerores sparse, at most 3 present on any abdominal segment and 3­5 present on any thoracic segment.

Ventral surface with setae similar to those on dorsum. Multilocular disc pores absent. Trilocular pores evenly distributed among setae. Oral collar tubular ducts similar to those on dorsum, sparsely present across abdominal segments and 1 or 2 situated laterally on thorax. Bitubular cerores, same size as those on dorsum, present singly near lateral margins of some abdominal segments, lateral to each thoracic spiracle and between antennal bases.

Material examined

HOLOTYPE adult Ψ, Falkland Islands, East Falkland, Cusby’s Hill, on roots of Bolax gummifera (Apiaceae) , extracted by Tullgren funnel apparatus, 7.xi.2002 (A.G. Jones) ( BMNH).

PARATYPES, Falkland Islands, same data as holotype, 2 adult ΨΨ, 3 3rd­instar ΨΨ, on same slide as holotype ( BMNH).

Etymology

The name is based on the Latin genitive of the host­plant name Bolax .

Comments

In possessing bitubular cerores and lacking multilocular disc pores, Rhizoecus bolacis is unlike any of the species so far described from the New World, which were discussed by Hambleton (1976) and Williams & Granara de Willink (1992). All the species of Rhizoecus Künckel d’Herculais presently known in the New World and possessing bitubular cerores also possess multilocular disc pores. Other species in the New World that lack multilocular disc pores also possess tritubular cerores instead of bitubular cerores. R. bolacis seems to be related to species known in southern Asia, many being described at present that lack multilocular disc pores but possess bitubular cerores. R. loicmatilei Williams , described from Thailand ( Williams, 2001), has a similar distribution of bitubular cerores and oral collar tubular ducts but the tubes in each ceroris are almost parallel, not divergent as in R. bolacis . Moreover, there are 2 circuli present in R. loicmatilei and each is cylindrical, whereas R. bolacis possesses a single, nipple­shaped circulus. Besides, there are eyes present in R. loicmatilei and the claw digitules are short and setose; in R. bolacis eyes are absent, and the claw digitules are knobbed and longer than the claw.

Figures

FIGURE 1. Rhizoecus bolacis sp. nov.