Chumma is a genuinely peculiar genus. First described in 2001 by Rudy Jocqué, it originally sat alone in its own monogeneric family, Chummidae, set apart from other spiders by an odd combination of traits. Only nine species have ever been described, all confined to southern Africa, with eight recorded from the southern parts of South Africa and one from the mountain enclave of Lesotho. Every species was described in just two publications, in 2001 and 2018, making the genus one of the least explored spider lineages in the region.

The family placement of Chumma has shifted dramatically over the past two decades, and the new study reflects that taxonomic turbulence. Molecular analyses using six genes led Wheeler and colleagues in 2017 to synonymize Chummidae with Amaurobiidae, and subsequent multi-gene studies by Crews and co-workers in 2020 and Kulkarni and co-workers in 2023 supported placing Chumma within the subfamily Macrobuninae. More recently, an analysis of ultraconserved elements by Gorneau and colleagues in 2023 elevated that subfamily to full family rank as Macrobunidae, and Chumma moved with it. In every one of these studies, Chumma was clearly nested within the Macrobuninae clade, usually as sister to the South African genus Chresiona, vindicating the synonymy of the old Chummidae with the newly defined Macrobunidae.

The path to the new species began with a compound microscope and a misleading first impression. While sorting spiders collected in the Western Cape, the first author noticed trionychan specimens in which only a single pair of spinnerets appeared visible. Only more precise examination using photography revealed the truth: six spinnerets were actually present, with two pairs so drastically reduced that they were effectively invisible under routine magnification. Discussions with the second author confirmed that the specimens belonged to Chumma, and the finding prompted a broader goal: describing the new species, documenting records collected since the genus was last treated in 2018, and commenting on its relationships.

Chumma foordi is known only from the type locality, where the holotype male, a paratype male and seventeen juveniles were collected in January 2017 by sifting litter in Afromontane forest. The species is named after the late Stefan Foord, honored for his contributions to the study of spider ecology and biodiversity, particularly in South Africa. The male measures just 2.83 millimeters in total length, with a carapace 1.14 millimeters long and an oval abdomen bearing a dorsal scutum that covers roughly three quarters of its length. The coloration is yellow to light brown dorsally and pale yellow ventrally, with dark radial stripes running across the carapace.

What sets the new species apart are features on the abdominal scutum and the male copulatory organ. Males of Chumma foordi carry a pair of deep round pits on the scutum, whereas in all other congeners such pits are either absent or elongate, and the new species also shows a lateral depression lacking in every other member of the genus. The palp, the male’s copulatory organ, bears four short tibial apophyses rather than the three seen in the superficially similar Chumma interfluvialis, and its tegulum is round rather than oval. The embolus is short, with a rounded anterior part and a straight posterior part, about four times longer than its maximal width, and the sperm duct runs along the lateral margin of the tegulum without any loops. The female remains unknown.

The study also documents the spinnerets of male Chumma in detail for the first time, using scanning electron microscopy on a gold-coated paratype. Under a light microscope, only two spinnerets can be recognized, but three pairs are actually present: the anterior lateral spinnerets are the largest, while both posterior pairs, the posterior median and posterior lateral spinnerets, are significantly reduced in size and can be considered vestigial. This vestigial arrangement echoes observations in other Macrobunidae genera, where Almeida-Silva noted that males with reduced posterior lateral spinnerets may lack spigots on them entirely. With the exception of Chumma, genera included in the family have no dorsal abdominal scuta, making the scutum another distinctive trait of this lineage.

Beyond the new species, the paper substantially expands the known footprint of the genus. Chumma bicolor, previously known only from its type locality at Goukamma in the Western Cape, is now recorded from three additional sites, including Bergplaas Road near Hoekwil, Bobbejaanskloof Private Nature Reserve near Plettenberg Bay, and Garcia Nature Reserve near Riversdale, where specimens were recovered by sifting litter in fynbos and Afromontane forest. At Bobbejaanskloof, Chumma bicolor occurs sympatrically with Chumma gastroperforata, meaning two species of this rare genus share the same patch of forest floor.

Chumma foliata, formerly known only from Hogsback, gains a new record from Clayputs Farm in the Grahamstown district of the Eastern Cape, collected by hand in March 2020. Chumma gastroperforata, the genus’ first described species, is now documented from five additional localities across the Western Cape, including Outeniqua Nature Reserve, Gondwana Game Reserve, Outeniquastrand near George, Bobbejaanskloof and Keurbooms Nature Reserve near Plettenberg Bay. The authors also correct the historical record: an earlier checklist had wrongly included five localities under Chumma gastroperforata, when only Witelsbos and Van Huyssteenbos remain valid, with the other paratypes reassigned to Chumma striata.

Perhaps the most striking result is a single subadult male from Nigramoep Slow Living Guest Farm in the Northern Cape, collected in January 2021 from leaf litter on a west-facing slope at 840 meters elevation. Although the specimen cannot yet be assigned to a described species, it represents the first record of Chumma from the Northern Cape Province, extending the genus’ range by more than 450 kilometers northwest. The authors suggest that Chumma likely occurs in Fynbos and Succulent Karoo biotopes along the western interior of South Africa as well, and that its apparent absence there reflects historically poor sampling rather than a genuine distributional gap. With the distribution of all species now mapped, the genus stands revealed as far more widespread than its nine species and two descriptive papers had suggested, waiting in the litter of southern Africa’s forests for better-sampled future surveys.

Subject of Research: Taxonomic description of a new Chumma spider species and new distribution records from South Africa

Article Title: A new species and new records of Chumma ( Araneae , Macrobunidae ) from South Africa

Article References: Marusik, Y. M., & Haddad, C. R. (2024). A new species and new records of Chumma (Araneae, Macrobunidae) from South Africa. African Invertebrates, 65(2), 329-338. https://doi.org/10.3897/afrinvertebr.65.138735

Image Credits: AI Generated

DOI: 10.3897/afrinvertebr.65.138735

Keywords: Chumma, Macrobunidae, spiders, taxonomy, South Africa, new species, species, records, Araneae, South, Africa, scientific research