Coccus pseudotumuliferus, 2018

Gullan, Penny J., Kondo, Takumasa, Fiala, Brigitte & Quek, Swee-Peck, 2018, Taxonomy of coccids (Hemiptera: Coccidae: Coccus L.) associated with Crematogaster ants (Hymenoptera: Formicidae) in the stems of Macaranga plants (Euphorbiaceae) in Southeast Asia, Zootaxa 4521 (1), pp. 1-51 : 9-11

Diagnosis for Coccus species associated with Macaranga .

Adult female. Unmounted material ( Fig. 2 ). Insects oval to elongate oval, generally less than 3.0 mm at widest point. Colour in life variable, from white, brown, yellowish-brown to red; covered in a thin layer of wax, with texture either smooth or somewhat finely granulose. Insects rather flat, not becoming convex, often with dorsal elevations. Generally associated with tending ants, and living within hollow stems of Macaranga plants.

Slide-mounted material. Body circular, oval or elongate oval, up to 4.5 mm long, 3.1 mm wide at maturity.

Dorsum: Derm membranous, generally with conspicuous areolations covering whole dorsum; derm not becoming heavily sclerotised at maturity. Dorsal tubercles and pocket-like sclerotisations absent. Dorsal setae variable, each sharply spinose, with a clubbed or rounded apex, or very short and about the same length as diameter of its setal socket. Dorsal tubular ducts absent. Dorsal microducts small, appearing bilocular under high magnification, each situated in an areolation, and scattered rather evenly throughout dorsum (since only found in areolations). Simple pores present, scattered evenly on dorsum. Preopercular pores scarce to numerous, generally small (each 5–10 µm diameter), present in a small to large, usually elongate, cluster anterior to anal plates, numbering 1–35 pores. Anal plates together quadrate to pyriform, inner lobes generally well developed, with a membranous fold of tessellated texture; each anal plate with 3–26 dorsal setae, 2 hypopygial setae, 2 ventral fringe setae and 1–4 ventral subapical setae. Anal ring almost entire, bearing a total of 8 or 10 setae, with 1 pair (if 8 setae) or 2 pairs (if 10 setae) thinner than the rest (setae difficult to count as obscured by ano-genital fold and easily confused with anterior margin setae). Sclerotised rim around anal plates absent.

Margin: Eyespots present or absent, when present located on margin or slightly on dorsal submargin. Marginal setae variable, each usually flagellate or sharply spinose with apex either tapering to a point, bifid or fimbriate, present in 1–3 rows. Stigmatic setae distinct from marginal setae, usually well developed, generally totalling 3, rarely 1 but sometimes up to 4 setae per stigmatic cleft; each seta sharply to bluntly spinose, median seta generally longer than lateral setae, but sometimes all setae subequal in length. Stigmatic clefts generally well defined. Spiracular furrow (or stigmatic groove) with a band of spiracular pores 1–4 pores wide, totalling usually 20–40 pores (number of pores difficult to count on most specimens), each pore 4–6 µm wide and with 2–7 (mostly 5) loculi.

Venter: Ventral derm membranous. Ventral setae slender, longest on posterior abdominal segments anterior to vulva. Interantennal setae numbering 2 or 3 pairs. Ventral tubular ducts present in a narrow or broad submarginal band, with tubular ducts also present on both sides of mouthparts (but usually absent anteriorly), across prothoracic and mesothoracic segments, often also present across metathorax or around metathoracic coxae. Ventral microducts present, scattered evenly on venter. Pregenital disc-pores each with 5–10 loculi, restricted to a small area on each side of genital opening. Antennae each 5–8 segmented. Mouthparts normal for coccids; clypeolabral shield with 1 pair of setae; labium with 4 pairs of setae. Legs normal in structure but often small in relation to body size, without tibiotarsal sclerotisation; tarsal digitules thin, one of each pair slightly thicker than the other, each with apex knobbed; claw digitules both knobbed, one thicker than other; claw denticle absent. Spiracles normal, often each set in a spiracular depression. Spiracular pores each with 3–7 (mostly 5, rarely an occasional pore with 2) loculi.

First-instar nymph. We were able to examine the first-instar nymphs of three species of Coccus , C. macarangae , C. penangenis and C. pseudotumuliferus , collected from Macaranga at one locality in Brunei. These nymphs could not be identified to species, although there may be small differences in body size, but our sample sizes were small and all of the nymphs were from one locality. We identified the first-instar nymphs as belonging to a particular species if they were collected from under the venter of an identified adult female. This was important because often more than one Coccus species occurred inside each Macaranga plant. Only the first-instar nymph of C. macarangae has been described and illustrated in the taxonomic section below. There is no modern and detailed description of the first-instar nymph of the type species of Coccus , C. hesperidum , although Borchsenius (1957) has a short description and Annecke (1966) provides a taxonomic illustration with reasonable detail. The available first-instar nymphs of Coccus species from Macaranga resemble the nymph of C. hesperidum illustrated by Annecke (1966) except that the latter is shown with spiracular pores of five loculi (four loculi in Macaranga nymphs) and quite straight marginal setae (there is a distinct bend at half-length in the marginal setae of Macaranga nymphs).

Slide-mounted material. Body oval to elongate oval, 330–490 µm long, 190–330 µm wide; stigmatic areas distinct, but sclerotised clefts absent.

Dorsum. Derm membranous. Dorsal setae minute, present in 2 submedial longitudinal rows on thorax and first abdominal segment. Trilocular pores on head not detected, but instead a pair of tiny simple pores present. Dorsal microducts and preopercular pores absent. Anal plates each longer than wide, elongate triangular with anterolateral margin subequal in length to posterolateral margin, and anterior margin rounded; each plate with 2 small dorsal setae near apex, 1 inner margin seta and an apical seta up to 150 µm long. Anal ring bearing 6 setae.

Margin. Eyespots present as pigmented spots on margin. Marginal setae robust flagellate and curved to bend posteriorly, present in 1 row, with always 2 setae between anterior and posterior stigmatic areas, 12 (rarely 11 or 13) on head between anterior stigmatic areas, and 8 on each side of abdomen. Stigmatic setae numbering 3 in each cleft, thicker than marginal setae; median seta longest, 2.0– 2.4 µm thick, spinose, slightly curved towards apex and apically rounded; lateral setae small, each ≤ 5 µm long, apically rounded.

Venter. Derm membranous. Ventral setae slender, 3 pairs of pregenital setae longest, other setae mostly minute, present in a marginal row around body and a submarginal row on each side of abdomen. Interantennal setae numbering 1 pair consisting of a single seta near base of each antenna. Ventral tubular ducts absent. Ventral microducts sparse, present submarginally with each side of body having 1 microduct between ventral setae on most abdominal segments, 2 microducts between anterior and posterior stigmatic areas, and 1 present between base of antenna and body margin. Disc-pores, except spiracular pores, absent. Antennae each 6 segmented; fleshy setae present on last 3 segments. Mouthparts typical of coccid nymphs. Legs normal; tarsal and claw digitules each with a small knobbed apex; claw with small denticle present. Spiracles normal; spiracular furrows each with 3 (anterior furrow) or 4 (posterior furrow) spiracular pores in a line.

Male instars. No adult or immature males were collected. One second-instar male and one pupa with a pharate adult male plus its prepupal exuviae were collected by PJG in Brunei from two different Macaranga plants but these belong to an undescribed species of Myzolecanium Beccari ( Gullan et al. 1993; Hodgson 1994). No other collections examined for this study contained any male coccids, and no publications on the Macaranga coccids report males; therefore, it is assumed that these Coccus species are parthenogenetic.

Species recognition. Delimitation of the Coccus species from Macaranga is confounded by geographic variation, probably exacerbated by lack of gene flow due parthenogenetic reproduction (as discussed in the Introduction). Several morphological features of adult females that typically are used to separate other Coccus species can vary substantially within a species in the Macaranga coccids, e.g., the shape and length of the marginal body setae and the number and size of the preopercular pores found anterior to the anal plates. The recent availability of a phylogenetic reconstruction for these coccids based on nuclear genes ( Quek et al. 2017) greatly assisted in recognising which morphological character states are taxonomically informative; thus, for this revision, we recognise each of the numbered clades presented in figure 3 of Quek et al. (2017) as a species, although four of them are based on very limited specimen sampling. In the case of clade 4 (C. near circularis ) and clade 9 (C. near macarangicolus ), we believe that these specimens are geographic variants of their respective species. Coccus circularis was described from a few specimens from Singapore ( Morrison 1921) and C. macarangicolus was based on just a few specimens from Kuala Lumpur ( Takahashi 1952), whereas the sequenced specimens are all from Borneo. We describe specimens of clade 3 (C. near tumuliferus ), clade 7 (C. sp. Y) and clade 8 (C. sp. X) as three new species, below.

Specimens of one new species represented in clade 3 of Quek et al. (2017) exhibit morphological variation of cuticular features and their live appearance also varies (see under C. pseudotumuliferus below). This may have led H.-P. Heckroth ( Heckroth et al. 1998; Heckroth, unpublished data) to recognise two morphospecies ( C. tumuliferus var. C. 84 and C. 214) for specimens that we are assigning to a single species.

As typical for all coccids, species of Coccus from Macaranga have been described based solely on the morphology of the adult females. Third-instar females of these Coccus species can be very difficult to distinguish from their adult females because they can be similar in size and have similar body setae. However, immature female soft scales rarely have multilocular pores near the vulva and their antennae each can have one or more fewer segments than those of adult females.

Morphospecies C. 41. Specimens referred to by this code number in Heckroth et al. (1998) were reported as found almost exclusively on the Bornean endemic M. winkleri (section Winklerianae), which was inhabited by Crematogaster morphospecies 8. This ant species is not part of the Crematogaster borneensis -group and its placement is unclear ( Feldhaar et al. 2016). All specimens of C. 41 (Heckroth collections numbers 41, 153 and 155) were collected in December 1992 in Lambir Hills National Park. All examined individuals of C. 41 are unusual in having the diagnostic features of a third-instar female (no multilocular pores near the vulva and 6- segmented antennae) but usually a body of the typical size of an adult. We hypothesise that they are probably immature specimens of C. penangensis , which may have failed to moult quickly to the adult due to some unsuitability of the host M. winkleri . Heckroth et al. (1998) reported that C. 41 never occurred in the same plant as C. penangensis (see their table 3, p. 436), although C. penangensis did occur on M. winkleri (fig. 1b, p. 434), and that C. 41 was uncommon. An immature female of C. macarangae (ID based in 12S DNA) sent by B. Fiala (No. 96) collected from M. winkleri at Tawau Hills, Sabah, on 7 April 2001, looks adult-like due to its body size (more than 2 mm long) and well-developed dorsal areolations; however, it also has no multilocular pores near the vulva and has 6-segmented antennae. This suggests that M. winkleri may generally be a poor host for the development of these Coccus species.

Figures

FIGURE 2. Live coccids and ants inside the cut stems of Macaranga plants: A, C. macarangae Morrison, in M. winkleri, Luasong, Sabah, Borneo (E. Linsenmair, 2003 BF #96); B, C. macarangae, in M. beccariana, Temburong, Brunei, Borneo (P.J. Gullan, PJG-B16); C, C. penangensis Morrison, in M. glandibracteolata, Poring, Sabah, Borneo (B. Fiala, 2003 BF #2); D, C. penangensis, in Macaranga sp., Temburong, Brunei, Borneo (P.J. Gullan, PJG-B31); E, C. pseudotumuliferus Gullan & Kondo sp. n., in M. pearsonii, Tawau, Sabah, Borneo (B. Fiala, 2003 BF #64); F, C. secretus Morrison, in M. indistincta, Tawau, Sabah, Borneo (B. Fiala, 2003 #95). All photographs taken by the collector specified in parentheses.