Formicococcus tectonae Joshi, Bindu & Gullan, 2020

Joshi, Sunil, Jose, Bindu K., Gullan, Penny, Sajeev, T. V. & Anoop, E. V., 2020, A new species of mealybug (Hemiptera: Coccomorpha: Pseudococcidae) from Tectona grandis L. f. (Lamiaceae) in southern India, Zootaxa 4718 (3), pp. 391-400 : 394-396

Formicococcus tectonae Joshi, Bindu & Gullan sp. n.

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Type material. Holotype adult ♀ on a slide together with four paratypes, INDIA, Kerala / Vettigapadam, Thrissur / Tectona grandis , 07.XII.2018 / Bindu Jose leg. / [ ICAR / NBAIR /PSEUDO/Form/71218-01]; holotype marked by encircling with permanent marker . Paratypes: 9 ♀♀, data same as holotype; four paratypes on the same slide as the holotype; the remaining five paratypes are mounted on a separate slide [ ICAR / NBAIR /PSEUDO/Form/71218-02]

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Description of the adult female.

Live appearance. Body oval or rotund, peach-pink; legs and antennae yellowish brown; bodies of nymphs and adult female covered by flocculent white mealy wax ( Fig. 1 F & G ), without bare areas on dorsum; intersegmental areas without mealy wax; very short lateral wax filaments present on abdominal segments, the pair on the last abdominal segment longer and curved; wax filaments absent from thorax and head. Ovisac absent; eggs gleaming cream ( Fig. 1 E ), laid singly, not covered with mealy wax powder. All life stages occurring on above-ground parts of host, under the bark in borer tunnels, and are sometimes attended by ants ( Fig. 1 D ).

Slide-mounted adult female ( Fig. 2 ). Measurements based on 10 type specimens. Body of adult female broadly oval to almost circular ( Fig. 2 A , Fig. 3 A ), membranous; largest specimen 3.05 mm long and 2.37 mm wide (holotype 2.05 mm long, 1.50 mm wide). Eyespots each 37–40 µm in diameter, not associated with discoidal pores. Antennae 7 segmented each about 320 µm long ( Fig. 2 B , Fig. 3 B ); apical segment 94–98 µm long and 25–27 µm wide. Labium 90–95 µm wide at base and 200–215 µm long, noticeably longer than clypeolabral shield, at about 190 µm long. Mesothoracic spiracles each 75–80 µm long including apodeme, 37–42 µm wide across peritreme; metathoracic spiracles each 82–87 µm long including apodeme, 45–55 µm wide across peritreme. Anal lobes well developed, ventral surface of each lobe bearing stout apical seta about 250 µm, bar seta 112–130 µm long, and anal lobe bar about 100 µm long ( Fig. 2 C , Fig. 3 C ), developed mainly forwards from bar seta. Legs well developed; hind trochanter + femur about 270–280 µm long, hind tibia + tarsus 240–260 µm long; claw stout, about 37–40 µm long. Ratio of lengths of hind tibia + tarsus to hind trochanter + femur about 0.96. Ratio of lengths of hind tibia to tarsus about 1.50. Hind trochanter with longest seta 62–70 µm long; tarsal digitules on each leg capitate, 50–55 µm long; claw digitules capitate, 30–33 µm long; claw denticle not discernible ( Fig. 2 D ). A total of 37–40 translucent pores present on anterior and posterior surfaces of hind coxa (22–26 on anterior surface and 14–15 on posterior surface) ( Fig. 2 E , Fig. 3 D , and translucent pores on posterior surface of hind tibia rare (2 out of 10 females with 6 to 7 pores on posterior surface) or absent ( Fig. 2 F , Fig. 3E ). Circulus present between abdominal segments III and IV irregular in shape ( Fig. 2 G ), 100–120 µm wide, divided by an intersegmental line. Trilocular pores unusual in appearance, with a smaller triangle containing 3 swirled loculi situated within a larger outer triangle ( Fig. 3 L ). Both pairs of ostioles well developed ( Fig. 2 H ); anterior ostioles 100–125 µm wide, each lip with 8–9 setae and 32–50 trilocular pores; posterior ostiole 52–62 µm wide, each lip with 7–8 setae and 40–51 trilocular. Anal ring 55–75 μm long and 65–85 μm wide ( Fig. 3 F ), situated at apex of abdomen; anal ring with 6 setae, each 90–95 μm long. Number of cerarii highly variable, their number varying from 11 to 15 pairs (only 1 out of 10 females examined possessed 18 clearly defined pairs of cerarii); all cerarian setae conical with flagellate tips. Anal lobe cerarii each bearing 4 or 5 conical setae ( Fig. 2 I , Fig. 3G ), each 22–28 µm long and about 7.5 µm wide at base, with 1 auxiliary seta and a few trilocular pores, all situated on a membranous area. Penultimate cerarii (C 17) each with 7 or 8 conical setae, 1 or 2 auxiliary setae ( Fig. 2 J , Fig. 3H ) and a few trilocular pores. Other abdominal cerarii as far forward as abdominal segment II each containing 2–5 conical setae, 1 or 2 auxiliary setae and few trilocular pores. Cerarii on thorax not discernible. Frontal cerarii each with 4 conical setae ( Fig. 2 K ), preocular cerarii each with 3 conical setae and ocular cerarii each with 2 conical and 1 auxiliary setae ( Fig. 2 L , Fig. 3I ). All cerarii each associated with a few trilocular pores.

Dorsal surface with thick, stiff setae each with a flagellate tip ( Fig. 2 M , Fig. 3 J ), of variable size, fairly numerous on median area. Smaller setae, each 12–17 μm long, medium setae each 25–30 μm long, and longer setae mostly each 35–37 μm long ( Fig. 3K ). Many setae each with 1 or 2 trilocular pores around setal collar. Even longer setae present dorsally just anterior to clypeolabral shield between antennal bases, each 55–65 μm long. Trilocular pores numerous ( Fig. 3 L ), evenly distributed, each about 5 µm wide. Discoidal pores ( Fig. 3 M ), each as wide as a trilocular pore, scattered. Oral collar tubular ducts and multilocular pores absent.

Ventral surface with flagellate setae ( Fig. 2 N , Fig. 3 N ), mostly each 20–67 µm long, but some on abdominal margins each 60–65 µm long. Ventral setae on head, just anterior to mouthparts, each about 75 µm long, whereas median areas of thorax and abdomen with setae each 25 to 67 μm long. Cisanal setae stout at base, each about 115 µm long; obanal setae each about 50 µm long. Multilocular disc pores each 9.8–10.0 µm in diameter ( Fig. 2 O , Fig. 3 O ), present posterior to vulva and medially at posterior edges of abdominal segments IV-VII; occasional pores also present on anterior edges of segments and on submargins of abdomen. Multilocular disc pores forming multiple transverse rows on abdominal segments VI and VII, a double row on V and a single row on segment IV. Trilocular pores same size and structure as those on dorsum but less numerous, evenly distributed. Discoidal pores scattered. Oral collar tubular ducts of 2 slightly different sizes present, both types narrower than a trilocular pore; wider type ( Fig. 2 P , Fig. 3 P ) present submarginally on abdominal segments VI and VII; and slender type ( Fig. 2 Q , Fig. 3 Q ) distributed across middle of abdominal segments V and VI, posterior to vulva, and in marginal groups on abdominal segments V–VIII.

Comments. Formicococcus tectonae is similar to F. robustus (Ezzat & McConnell) in having more than 3 conical setae in most cerarii including the anal lobe pair; cerarii on the abdomen containing auxiliary setae; and similar distributions of ventral oral collar tubular ducts and types of dorsal and ventral setae. Formicococcus tectonae can be distinguished (characters of F. robustus given in parentheses) by having (i) multilocular pores on segments IV–VIII (V–VIII); (ii) cerarian setae conical with flagellate tips (conical but sometimes 1 or more setae with flagellate tips); and (iii) by the absence or rarity of translucent pores on the hind tibia (present). Formicococcus tectonae is also similar to F. polysperes Williams in having multilocular disc pores as far forward as abdominal segment IV, but differs (characters of F. tectonae given in parentheses) in having stout, stiff dorsal setae (thick, stiff setae with a flagellate tip) and in having oral collar tubular ducts on the thorax and head (oral collar ducts absent from thorax and head).

In view of the unusual structure of the trilocular pores in F. tectonae sp. n., those of some other species of Formicococcus were examined to see if this feature is shared with congeneric species. Trilocular pores with a similar structure were observed in F. lingnani , F. polysperes and F. formicarii .

Etymology. We have named this new species after the genus of the host plant ( Tectona ) on which it was collected; the name is in the genitive singular.

Biological notes. At the first location ( Fig. 1A ), 36 of 45 trees (80.0 %) were infested by trunk borer to various degrees, whereas at the second location 40 of 55 trees (72.7 %) were infested. The trunks of borer-infested trees had a twisted appearance ( Fig. 1 B ). Each moth larva was found to make four to five entry holes in the trunk and produce tunnels while feeding on the heartwood ( Fig. 1C ). At both locations, all the borer-infested trees had mealybug populations. Mealybugs were found only at the entrance of the passageways made by the moth larvae. It is doubtful if there is any reciprocal relationship or even a dependency of the mealybug on the moth larvae, although the tunnels made by the borer provide suitable habitat for the mealybugs. Further studies are needed to investigate the association of these insects.

No parasitoids or predators of the mealybugs were obtained from the collections made in the present study. In the field, ants of an unidentified species of Tapinoma Foerster were found attending the mealybugs. In the first location, ants were found on 12 out of 36 mealybug-infested trees (33.3 %), while at second location, ants were found on 9 out of 40 infested trees (22.5 %).

Figures

FIGURE 1. A. Site of observations in the Palappalli forest range; B. Teak tree affected with trunk borer, Cossus cadambae; C. Entry holes made by the larvae of trunk borer; D. Infestation of Formicococcus tectonae Joshi, Bindu & Gullan at the entry hole of the borer and an ant attending the mealybugs; E. Eggs of F. tectonae; F. Nymph hidden under the loose bark; G. Adult female.

FIGURE 2. Diagnostic features of a slide-mounted adult female of Formicococcus tectonae Joshi, Bindu & Gullan. A. Female broadly oval to rotund; B. Antenna with seven segments; C. Anal lobe bar with bar seta; D. Claw without a denticle; E. Hind coxa with translucent pores; F. Hind tibia without translucent pores; G. Circulus irregular in shape; H. Ostiole well developed; I. Anal lobe cerarius with 4–5 conical setae and 1 auxiliary seta; J. Penultimate cerarius with 7 or 8 conical and 1 or 2 auxiliary setae; K. Frontal cerarius with 4 conical setae; L. Ocular cerarius with 2 conical and 1 auxiliary seta; M. Dorsal seta thick and stiff; N. Ventral setae flagellate; O. Multilocular disc pores; P. Submarginal oral collar tubular ducts; Q. Median oral collar tubular ducts.

FIGURE 3. Taxonomic illustration of an adult female of Formicococcus tectonae Joshi, Bindu & Gullan. A. Body derm; B. Antenna; C. Ventral surface of anal lobe showing anal lobe bar; D. Coxa with translucent pores; E. Tibia without translucent pores; F. Anal ring with 3 pairs of setae; G. Anal lobe cerarius; H. Penultimate cerarius; I. Preocular cerarius; J. Dorsal seta (shorter type); K. Dorsal seta (longer type); L. Trilocular pores (dorsal and ventral); M. Discoidal pores (dorsal and ventral); N. Ventral seta; O. Multilocular disc pore; P. Tubular duct on marginal area; Q. Tubular duct on median area.