Scymnus (Scymnus) hodeki Poorani, 2023

Poorani, J. & Thanigairaj, R., 2023, A new species of Scymnus Kugelann (Coleoptera: Coccinellidae) predatory on amla aphid, Schoutedenia emblica (Patel & Kulkarni) (Hemiptera: Aphididae) from India, Zootaxa 5239 (3), pp. 421-430 : 422-429

publication ID	https://doi.org/ 10.11646/zootaxa.5239.3.6
publication LSID	lsid:zoobank.org:pub:9990FC2E-D667-4268-9DCA-9F745259E577
DOI	https://doi.org/10.5281/zenodo.7639169
persistent identifier	https://treatment.plazi.org/id/AE0E4029-FF9C-FFC1-FF73-891EFCA04CE4
treatment provided by	Plazi
scientific name	Scymnus (Scymnus) hodeki Poorani
status	sp. nov.

Treatment

Scymnus (Scymnus) hodeki Poorani , sp. n.

( Figs 2–4 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Diagnosis. Scymnus (Scymnus) hodeki sp. n. is externally similar to Scymnus (Pullus) castaneus Sicard , one of the most common Scymnini in southern India. It can be separated from the latter by the incomplete abdominal postcoxal lines, more broadly separated and subparallel prosternal carinae and the male genitalia. Scymnus castaneus belongs to the subgenus Pullus Mulsant and it has complete postcoxal lines, distinctly divergent prosternal carinae and the male genitalia, particularly the penis and its apex, are different.

Description. TL: 1.95–2.07 mm, TW: 1.62–1.75 mm; TL/TW: 1.18–1.20, PL/PW: 0.32–0.44; EL/EW: 0.96– 1.01. Male. Form elongate to short oval, dorsum convex and densely pubescent with silvery white hairs ( Fig. 2a–d View FIGURE 2 ). Dorsal side reddish brown to yellowish-ochraceous, ventral side yellowish brown, occasionally metaventrite anteriorly with darker brown areas. Head ( Fig. 2e View FIGURE 2 ) about 3.65–3.70× as wide as an eye, interocular distance 1.60– 1.80× as wide as an eye; punctures on head uniform, separated by 1–2 diameters. Antenna ( Fig. 2f View FIGURE 2 ) 11-segmented with a three-segmented club. Pronotum densely punctate with shallowly impressed punctures, punctures separated by 0.5–2.0 diameters. Elytra with a pair of short, somewhat irregular rows of punctures on either side of suture, punctures on these rows larger and coarser than other discal punctures, separated by less than their own diameter; rest of elytra with dense punctures separated by 0.5–2.0 diameters, slightly more broadly spaced towards apices. Prosternal intercoxal process ( Fig. 2g View FIGURE 2 ) with a pair of almost parallel, apically divergent carinae; area enclosed by carinae with a few large punctures roughly forming two rows. Mesoventrite ( Fig. 2g View FIGURE 2 ) anteriorly broadly and very shallowly emarginate. Abdominal postcoxal line ( Fig. 3a, b View FIGURE 3 ) incomplete, apically slightly recurved, area enclosed by postcoxal line with dense, small punctures in the anterior two-thirds, apical one-third closer to postcoxal line devoid of punctures. Posterior margin of ventrite 5 medially broadly emarginate, that of ventrite 6 subtruncate to barely emarginate ( Fig. 3a View FIGURE 3 ). Tarsal claws double with a sharp basal angulation, inner claw shorter than outer one. Male genitalia ( Figs. 3c–f View FIGURE 3 ) with penis guide gradually narrowed towards a pointed apex in lateral view ( Fig. 3c View FIGURE 3 ), broad, lanceolate-conical in ventral view ( Fig. 3d View FIGURE 3 ), distinctly shorter than parameres, with few short lateral and apical setae; penis ( Fig. 3e, f View FIGURE 3 ) with a well-developed, broad capsule having a wide outer arm and a much shorter and narrower inner arm, apex modified as illustrated.

Female. Externally similar to male except posterior margin of ventrite 5 truncate and that of ventrite 6 weakly arcuate. Female genitalia ( Fig. 3g View FIGURE 3 ) with elongate triangular coxites having prominent styli, infundibulum absent; spermatheca ( Fig. 3g, h View FIGURE 3 ) as illustrated, without a distinct nodulus and ramus, cornu strongly curved.

Material examined. Holotype male: “ India: Tamil Nadu: Podavur, NRCB Research Farm, N 10°47’20.16” E 078°34’29.88” / Feeding on Schoutedenia emblica on amla, 20.vii.2022, R. Thanigairaj” ( NBAIR) GoogleMaps . Paratypes: 5 females and 5 males with the same data ( NBAIR) GoogleMaps ; 40 ex., unsexed, with voucher codes NRC-AA-4773 to NRC-AA-4813 ( NCBS). Numerous other specimens with the same data as paratypes GoogleMaps .

Distribution. India: Tamil Nadu.

Etymology. This species is named in honour of Ivo Hodek, the eminent Coccinellidae expert, who passed into the ages recently.

Biology. The larvae ( Fig. 4a–c View FIGURE 4 ) are characteristic of the tribe Scymnini and are pale yellowish with dense white waxy filaments on the dorsal and lateral sides and feed on all stages of the aphid. The pupa ( Fig. 4d–f View FIGURE 4 ) is yellowishorange with white waxy filaments on the dorsal and lateral sides. Pupation takes place in groups beneath the bark and other natural crevices in the amla tree and also at the base of the trunk near the soil. Groups of pupae were also observed inside left-over pupal cases of Lepidoptera ( Fig. 4e View FIGURE 4 ) and other pieces of debris on the amla trees.

The life cycle of Scymnus (Scymnus) hodeki sp. n. from oviposition to adult emergence took 16–19 days in laboratory conditions (observations based on 50 larvae). There were four larval instars with the larval period lasting 7–8 days. The pupal period was 3–4 days.

In our extensive collections of Scymnini associated with the sucking pests of various agricultural and horticultural crops from the same locality over the last few years, Scymnus (Scymnus) hodeki sp. n. was collected only on amla. In laboratory studies, it did not feed on other aphids. This suggests that it is a highly host- and host plant-specific species of Scymnus .

Natural enemies. Heavy parasitism of the pupal stage of Scymnus (Scymnus) hodeki sp. n. was observed in the field ( Figs 4g, h View FIGURE 4 ; 5a, b View FIGURE 5 ). The pteromalid parasitoid, Pachyneuron sp. ( Hymenoptera : Pteromalidae ) was found to be the most common, causing up to 70% pupal parasitism. Parasitized pupae are readily recognized by their dark brown to black colour ( Fig. 4g View FIGURE 4 ). When discoloured pupae are dissected open, parasitoid larvae and pupae at various stages ( Figs 4h View FIGURE 4 , 5a, b View FIGURE 5 ) could be seen. The adult of Pachyneuron sp. is dark bluish black ( Fig. 5c, d View FIGURE 5 ) with a metallic sheen. Another parasitoid, Homalotylus albiclavatus (Agarwal) ( Hymenoptera : Encyrtidae ) ( Fig. 5e View FIGURE 5 ) was also recorded at much lower levels. It is known to be a primary parasitoid of unidentified Coccinellidae and Pullus sp. and is also associated with various mealybugs and aphids (Noyes 2019).