Plokiophilidae, the family to which the new species belongs, comprises small predatory true bugs whose body lengths range from 1.10 to 3.00 millimetres. Nine genera and 24 species have been recorded so far, including one fossil genus and one fossil species preserved in Baltic amber. The family sits within the cimicomorphan superfamily Cimicoidea and is hypothesized to be the sister group to the bed bugs (Cimicidae) and their close relatives Curaliidae and Polyctenidae. What makes these insects remarkable is their lifestyle: most members spend their entire lives on the webs of spiders or webspinners (embiopterans), feeding on the host’s food, eggs, juveniles and weakened adults, as well as on other small arthropods trapped in the web. They are rarely collected, although a few species have turned up in flight interception and Malaise traps and in soil and leaf litter samples.

The taxonomic history of the family stretches back nearly a century. China and Myers discovered the first species, Arachnophila cubana, on the webs of a spider in Cuba in 1929 and tentatively placed it in the family Microphysidae. Because the generic name clashed with an older bird genus, it was revised to Plokiophila in 1953, when the subfamily Plokiophilinae was also established for a new species found on webspinner webs in Trinidad. Carayon recognized Plokiophilidae as a family distinct from Microphysidae in 1961 and divided it into two subfamilies based on host differences, later adding one new genus and seven new species from continental Africa and Brazil. Schuh described the genus Heissophila in 2006 from material collected in Chiang Mai, Thailand, but its subfamilial placement remained uncertain for years because the group lacks the traumatic insemination structures seen elsewhere in the family.

The resolution came in 2015, when Schuh and colleagues, working from male and female genital structures of additional specimens, established the new subfamily Heissophilinae and placed Heissophila within it. Until now the genus contained a single described species, Heissophila macrotheleae, known from Thailand, Indonesia and China. The new Chinese material came to light during recent field investigations: a series of specimens was collected from the webs of an Orientothele spider in Fujian, and further specimens arrived from the webs of Vacrothele spiders in Guangdong Province. Examination showed that all of them represent one new species.

The type specimen, an adult male, was collected in Qishan National Forest Park in Minhou, Fuzhou, Fujian, at roughly 77 metres elevation on 28 September 2025. Paratypes include additional males, females and nymphs from the same locality, more specimens from Fujian Agriculture and Forestry University in Yanping, Nanping, and material from two Guangdong sites: Longdong Reservoir in Guangzhou and Daling in Xinhui, Jiangmen. The specimens are deposited in the Entomological Museum of China Agricultural University in Beijing, with duplicates from Guangdong held at the South China Agricultural University. The Chinese vernacular name of the new species is 中华海丝蝽.

Heissophila sinica is a minute insect, with body lengths of 1.1 to 1.4 millimetres. Most individuals are brachypterous, meaning they have shortened wings; only one macropterous, fully winged female was recorded. In the brachypterous form the hemelytra, the thickened front wings, cover only the first five abdominal segments and are elevated and elytron-like, while the hind wings are reduced to small, triangular, veinless pads. The hemelytral membrane itself lacks veins entirely, a striking departure from the four-veined membrane of H. macrotheleae. The corial glands, a signature feature of the genus, are numerous but small, circular and droplet-shaped, convex from base to apex, with a single gland pore located on the convexity, and they occur only on the corium and clavus of the hemelytra. In the older species the glands also appear on the pronotum and the second antennal segment, and their pores sit within a depression surrounding a central convexity.

Detailed measurements underline how small the new species is. The brachypterous male holotype measures 1.20 millimetres in body length, with paratype males ranging from 1.18 to 1.24 millimetres and brachypterous females from 1.29 to 1.36 millimetres; the single macropterous female reaches 1.36 millimetres. The antennae are slender, with the second and third segments nearly equal in length, whereas in H. macrotheleae the second segment is distinctly longer than the third. The second tarsomere is clearly shorter than the third, another contrast with the older species, in which the two are nearly equal. The male genitalia also differ: the pygophore of H. sinica is subglobose in lateral view and lacks a dorsal thumb-like projection, and the apical portion of the parameres is nearly straight, while H. macrotheleae has a subtriangular pygophore with a thumb-like projection and curved paramere tips.

Despite the veinless membrane, the authors assigned the new species to Heissophila rather than erecting a new genus. H. sinica matches all the original diagnostic characters of the genus except the venation, and because the presence or absence of veins and the formation of cells in the membrane vary among species in the related genera Plokiophiloides and Neoplokioides, the team followed conservative taxonomic practice and revised the generic diagnosis instead. Under light microscopy the male was found to possess a tubular endosoma and the female well-developed ovipositor valves internally, with no traumatic insemination structures, confirming placement in Heissophilinae. The authors note that the species’ exact taxonomic placement requires further investigation based on additional material.

The discovery also redraws the map of the genus. Heissophila macrotheleae is recorded from several provinces of Thailand, from East Kalimantan in Indonesia, and from Yunnan Province in China. The new study adds provincial records from Longzhou County in Guangxi, Dongfang City in Hainan, and Yanping District in Fujian, based on specimens collected from the webs of unidentified macrothelid spiders in recent years. These localities bridge the previously known Yunnan populations of H. macrotheleae and the Fujian and Guangdong populations of the new species, suggesting that the genus may have a more continuous distribution along southern China’s coastal and sub-coastal regions than previously appreciated.

The host associations reveal an equally interesting pattern. In Fujian the host of H. sinica is Orientothele, while in Guangdong it is Vacrothele; both genera belong to the Macrothelidae, the same spider family that hosts H. macrotheleae through its association with Macrothele species. This indicates that Heissophila bugs show fidelity to the host family while remaining flexible at the genus level, a strategy that the authors suggest may allow broader geographic dispersal without requiring strict co-speciation, potentially explaining the genus’s wide yet disjunct distribution. Field observations at Qishan National Forest Park, where more than 50 Orientothele webs were examined on shaded, moist soil slopes, found the bugs exclusively on small to medium-sized webs built by juvenile spiders, never on large adult webs, with populations of two to six adults and nymphs per web and all field-collected adults brachypterous. Preliminary laboratory rearing at 25 degrees Celsius and 60 percent relative humidity showed yellow eggs appearing on webs after three days, an incubation period of about six days, and nymphs moulting to adults roughly 35 days after hatching; after two generations, one macropterous female appeared. The authors hypothesize that the short-winged form suits movement within webs while fully winged individuals develop for dispersal when web population density becomes too high, an idea they stress requires further experimental verification.

Subject of Research: Taxonomic description of a new web-inhabiting true bug species from China and its spider host associations

Article Title: A new species of the web-inhabiting bug genus Heissophila Schuh ( Hemiptera , Plokiophilidae ) from China, with notes on host associations for the genus

Article References: Xiong, H., Chen, Z., Li, H., & Cai, W. (2026). A new species of the web-inhabiting bug genus Heissophila Schuh (Hemiptera, Plokiophilidae) from China, with notes on host associations for the genus. ZooKeys, 1296, 11–25. https://doi.org/10.3897/zookeys.1296.200871

Image Credits: AI Generated

DOI: 10.3897/zookeys.1296.200871

Keywords: Heissophila sinica, Plokiophilidae, new species, China, Hemiptera, Macrothelidae, spider webs, taxonomy, brachyptery, host associations, ZooKeys, entomology