Rhizoecus peripotaro Schneider & LaPolla, 2024

Schneider, Scott A. & Lapolla, John S., 2024, New species of Coccidella Hambleton and Rhizoecus Kunckel d’Herculais from South America (Hemiptera: Rhizoecidae), Zootaxa 5555 (1), pp. 125-133 : 128-131

Rhizoecus peripotaro Schneider & LaPolla sp. nov.

Fig. 2

Material examined. Holotype. GUYANA: 1 adult ♀, Camp on Potaro River at base of Mt. Ayanganna, Dicymbe forest, from Acropyga goeldii nest, 5.3033, -59.9113, elev. 695m, 8.x.2002, J.S. LaPolla leg., USNM (nest ID JSL021008-04 a-b, prep S0755A).

Paratypes. GUYANA, all with same data as holotype : 1 adult ♀, USNM (nest ID JSL021008-04 a-b, prep S0755B) ; 2 adult ♀♀, USNM (nest ID JSL021008-04 a-b) ; 2 adult ♀♀, USNM (nest ID JSL021008-04 a-b) ; 2 adult ♀♀ and 1 immature in poor condition, USNM (nest ID JSL021008-04 a-b) ; 3 adult ♀♀ and 1 immature in poor condition, USNM (nest ID JSL021008-04 a-b) .

Non-type material. PERU: all specimens from Cusco, Manu (Villa Carmen) Biological Station , from Acropyga goeldii nest, -12.8947, -71.4038, 6.viii.2013, J.S. LaPolla leg.: 1 adult ♀, USNM (nest ID JSL130806-12 , prep S0093A) ; 1 adult ♀, USNM (nest ID JSL130806-12 , prep S0093B) ; 1 adult ♀, 7.viii.2013, USNM (nest ID JSL130807-01 , prep S0431A) ; 4 adult ♀♀ mounted on separate slides, USNM (nest ID JSL130806-12 ) .

Description. Adult female (N=11).

Appearance in life not recorded.

Description of the slide-mounted adult female. Body broadly oval to subcircular and membranous, 0.81–0.90 mm long, 0.61–0.69 mm wide at widest point near abdominal segment II. Eyes absent. Antennae geniculate, each 5 segmented, situated ventrally on submedian of head; overall length 103–114 µm; segment lengths (in µm): segment I, 27–33; II, 12–15; III, 12–15; IV, 13–15, and V, 36–41. Antennal setae mostly flagellate, 11–28 µm long, longest setae on the apical segment, together with 3 falcate sensory setae. Cephalic plate present, sclerotized. Labium 3 segmented, 65 µm long, 45 µm wide. Anterior and posterior pairs of spiracles each about 18 µm in diameter. Legs well developed, measurements in µm: hind leg 229–234, coxa 30–34, trochanter + femur 85–91, tibia + tarsus 87–92, claw 19–24; ratio of trochanter + femur / tibia + tarsus 0.92–1.02 (average 0.97). Leg setae mostly flagellate, each 9–27 µm long; tarsal digitules stout flagellate; claw digitules simple and shorter than claw (about 5 µm long). Anterior ostioles present but poorly developed, each 8–11 µm in diameter (average 9.4 µm) with minor sclerotization around rim; posterior ostioles indistinct in type series, if present, weakly developed and without sclerotization. Anal lobes poorly developed, each bearing 3 distinctly enlarged setae, 34–48 µm long. Anal ring about 46 µm in diameter, with 2 rows of cells, all without apparent spicules; ring bearing 8 setae, 6 larger setae 41–49 µm long and 2 smaller setae situated at posterior apex, each about 20 µm long. Internal genital organ heavily sclerotized.

Venter. Body setae flagellate, each 7–10 µm on head, 7–13 µm on thoracic segments, 7–20 µm on abdominal segments. Multilocular disc-pores present: on abdomen, 12–20 pores situated near vulva on segments VI – VIII, with some variation in distribution among type series, 1 specimen also bears 1 submedial disc-pore on each of segments III and V; on thorax: 1 or 2 pores situated near each anterior spiracle but often with lopsided distribution, present on one side of the body only; 1 specimen also bears 1 pore near posterior spiracle on one side; most multilocular disc-pores apparently each with 8 loculi. Tritubular cerores absent. Trilocular pores numerous, each about 3 µm wide, distributed among body setae. Oral collar tubular ducts absent. Circulus absent .

Dorsum. Body setae flagellate, each 7–10 µm long on head, 6–11 µm on thoracic segments, 7–20 µm on abdominal segments. Submedial multilocular disc-pores present, number variable and often asymmetrical in distribution; situated most consistently on mesothorax, metathorax, and abdominal segment I, flanking median tubular cerores but often unpaired or with 2 pores to one side; also occasionally present on segments II or III. Tritubular cerores present, each about 7 µm in diameter; situated on margin of prothorax, mesothorax, metathorax, and abdominal segments II–V and VII; medial cerores present on prothorax, mesothorax, metathorax, and abdominal segments I–III and V. Trilocular pores numerous, each about 3 µm wide, distributed among body setae. Oral collar tubular ducts absent.

Etymology. The epithet is an adjective formed from Potaro, the name of the river basin where it was discovered, combined with the Greek prefix peri -, meaning near or around.

Comments. Following Kozár & Konczné Benedicty (2007), the presence of tritubular cerores and the weak development of the anal lobes in R. peripotaro places it within their concept of subtribe Rhizoecina , but it cannot be referred to the other genera of this group because it lacks (i) clavate setae, (ii) 5-locular pores, and (iii) groups of pores on the venter or around tritubular cerores. The new species fits within the general description of Rhizoecus in having (i) tritubular cerores, on the dorsum only in this case, and (ii) flagellate body setae. It departs from the norm for Rhizoecus by possessing 8 anal ring setae—the 6 robust setae typically found in other species, plus 2 additional shorter setae at the posterior apex of the ring.

A distinctive trait of R. peripotaro relates to the variable and asymmetrical distribution of multilocular disc-pores, particularly those on the dorsum. Dorsal multilocular disc-pores are present in each specimen of the type series but vary in which segments they occupy (mesothorax through abdominal segment II) and whether they are symmetrically paired or lopsided in distribution around the medial tritubular cerores. For example, one paratype has 1 submedial pore on the mesothorax (unpaired), 2 on the metathorax off to one side, a pair on abdominal segment I flanking the medial ceroris, and 1 (unpaired) on segment II. Multilocular disc-pores located near the spiracles are also asymmetrically distributed, sometimes with 1 or 2 pores located near the anterior spiracle on one side of the body only.

Rhizoecus peripotaro is similar in appearance to R. compotor Williams & Granara de Willink. It can be distinguished by having (character states of R. compotor are given in parentheses): dorsal multilocular disc-pores present (absent); with 12 or more ventral multilocular disc-pores near the vulva (only 3 in holotype); anterior ostioles with some sclerotization of the rim (anterior ostioles absent); and by lacking spicules in the outer row of anal ring cells (spicules present). In a previous publication, R. peripotaro was referred to as Rhizoecus near compotor ( Sodano et al. 2024) .

The type series was collected in Guyana in 2002 from a nest of A. goeldii and was observed to be actively attended by worker ants. Subsequently, in 2013, another nest of A. goeldii from Peru was found containing mealybugs nearly identical to the type series of R. peripotaro , the only obvious difference being that their posterior ostioles are more developed and lightly sclerotized than in the type series. We tentatively recognize both samples as members of the same species.

The key to Neotropical adult females of Rhizoecus by Kaydan et al. (2019) can be modified (at couplet 17) to include R. peripotaro by using the following:

17 Anterior pair of ostioles present......................................................................... 18 - Anterior pair of ostioles absent............................................. R. granaradewillinkae Kaydan & Szita 18 Tritubular cerores present on venter..................................................................... 18a - Tritubular cerores absent from venter................................... R. peripotaro Schneider & LaPolla sp. nov. 18a Ostioles heavily sclerotized................................................................. R. caladii Green - Ostioles membranous................................................................................. 19

Figures

FIGURE 2. Rhizoecus peripotaro sp. nov. Adult female, full body view, illustrated from the holotype and paratypes. Illustration by SAS.