Family Heleophrynidae

Heleophryne hewitti Boycott, 1988

Hewitt’s Ghost Frog, Hewitt se Spookpadda (A)

By R.C. Boycott

Currently accepted name: Heleophryne hewitti
Red listing status: Critically Endangered

RED LIST SPECIES

Status: Critically Endangered (CR) Criteria: B2ab(ii,iii,iv,v)

Identification

This medium-sized species attains a snout–vent length of 50 mm in females and 47 mm in males, and has the long legs, spatulate digits and squat posture characteristic of Heleophryne. The dorsum is uniform light brown to olive brown and bears large, rounded to irregular dark spots with thin, light margins. The spots coalesce on the legs, forming dark transverse bands. The distinctive call consists of a sequence of 8–9 soft, repetitive whistles about 1.5 s apart. Call bouts, particularly those separated by 8–10 s intervals, commence with a long, loud note, produced as a drawn-out whistle about 250 ms long. The notes forming the rest of the bout are about 60–110 ms long and have an emphasized frequency range of 1.7–2.2 kHz (Boycott 1988a; Boycott and Branch 1988; Passmore and Carruthers 1995; Channing 2001).

The atlas data are reliable and up to date.

Distribution

H. hewitti is endemic to the Eastern Cape Province of South Africa. Its distribution is limited to the Elandsberg range where it is restricted to four rivers: the Geelhoutboom, Martin’s, Klein and Diepkloof rivers. Only the Martin’s and Klein rivers have perennial tributaries, and the sources of the four rivers extend over a distance of just 10 km. The greatest distance separating any two of these rivers is 3.5 km. The recorded altitudinal range is 400–550 m (Boycott and Branch 1988). Historically the species is only known from three quarter-degree grid cells, and no further grid cells were added during the atlas period.

The relationship between H. hewitti and presently unidentified Heleophryne populations in the Kammanassie, Kouga and Baviaanskloof mountains, requires investigation (Boycott and Branch 1988; Branch and Bauer 1995; Harrison et al. 2001). Tadpoles recently collected from the southeastern slopes of Cockscomb (3324DB) in the Grootwinterhoek Mountains were tentatively identified as H. hewitti, but await verification (M. Cunningham pers. comm.)

Habitat

H. hewitti inhabits the upper reaches of clear, swift-flowing, perennial mountain streams with rocky beds, in an area with annual rainfall of c.1000 mm. Adults and tadpoles are found beneath submerged and partly-submerged rocks in these streams, and occasionally at the edge of small waterfalls and cascades (Boycott and Branch 1988). It is assumed that the adults leave the streams during the non-breeding season to forage in surrounding terrestrial habitat, as is the case in other Heleophryne species.

The Elandsberg range lies within the Fynbos Biome, and H. hewitti occurs in Grassy Fynbos on the southern, relatively mesic slopes. However, there are only remnant patches of fynbos because most of the natural vegetation has been replaced by plantations of exotic trees that extend virtually onto the stream banks. Thus little non-breeding habitat is available to this species.

Life history

Nothing is known of the non-breeding behaviour of H. hewitti. Calling males have been heard October–November, indicating a similar breeding period to that of H. purcelli and H. orientalis. Males call at night and during the day under large, flat, partly submerged rocks in shallow, fast-flowing sections of streams. These rocks usually rest on top of smaller rocks, and the calling males take refuge in the spaces between the latter. Males have also been found calling from the sides of rocky gullies through which the stream flows, taking up positions directly above and within centimetres of the rushing water.

Gravid and spent females and eight egg batches were found in October (Boycott 1988). The eggs were large and yellow and numbered 93–150 per clutch. They were laid under submerged or partly submerged rocks of variable size, usually in relatively quiet backwaters where stream flow was not rapid and water depth was 20–60 cm. However, one batch was attached to the underside of a rock in a shallow, fast-flowing stream. As with all species of ghost frog, the tadpoles of H. hewitti are more easily located than the adults and, in some instances, distribution records for the species have been based solely on tadpoles. Tadpoles and adults are preyed upon by the common Brown Water Snake Lycodonomorphus rufulus (pers. obs.).

Conservation

Status

H. hewitti was previously listed as Endangered (Branch 1988). Its present status is Critically Endangered, based primarily on an extent of occurrence <100 km², as well as substantial loss, fragmentation and degradation of its habitat, and projected decline in its area of occupancy and the absence of protection within a nature reserve (Harrison et al. 2001; this publication).

Heleophryne hewitti is a protected species under the Cape Nature Conservation Ordinance (Ordinance 19 of 1974, as amended) and the SAFCOL (South African Forestry Company Limited) Environmental Policy, according to the standards of the Forest Stewardship Council (FSC) (Harrison et al. 2001).

Threats

H. hewitti appears to have one of the most restricted distribution ranges of any southern African amphibian, and that in an area dominated by alien pine plantations. The species is threatened by habitat loss, fragmentation and degradation as a result of over-utilization of its habitat for forestry, frequent and sometimes devastating forest fires and floods. In the 1980s, mountain fires devastated the whole region and during subsequent clean-up operations, many burnt trees were felled and left in the watercourses. Thereafter, heavy rains washed much of the felled timber and debris into the streams, blocking the flow and causing siltation of virtually every stretch of Heleophryne habitat, including the type locality. Other possible threats to the species include the construction of dams, and the introduction of alien fish species (Boycott and Branch 1988; Harrison et al. 2001).

Recommended conservation actions

Priority needs to be given to the conservation and management of remaining H. hewitti breeding and non-breeding habitats. The absence of protection for H. hewitti within a provincial or private nature reserve is a serious concern. Harrison et al. (2001) recommended monitoring of known populations, an intensive search for new populations, and an investigation of the taxonomic relationship between H. hewitti and other Heleophryne populations in the vicinity. They also suggested that a population and habitat viability assessment (PHVA) be carried out and that the public be informed of the plight of this species.

Over the last two decades the habitat of H. hewitti has deteriorated alarmingly. This may be attributed solely to mismanagement of, and blatant disregard for, the habitat of an endangered species. H. hewitti was classified as an endangered species in 1988, shortly after its discovery. During a June 2002 visit to the Geelhoutboom River type locality and Martins River, the habitat was found in a shocking condition. Both localities were heavily infested with alien pine and wattle trees. In particular, the type locality was sedimented to such a degree that pine trees were growing in the riverbed. On account of the sedimentation there has been a considerable reduction in the breeding habitat where riffles, rapids and rocky pools have been buried under sand. High levels of algal growth were evident, probably as a result of the elimination of invertebrate fauna and the loss of direct sunlight due to trees growing in and over the river.

To recover some of the former breeding habitat, it is imperative that action be taken immediately. All alien trees (pine and wattle) must be cut down and removed from the riverbed and the riverbanks. These should be cut and removed manually from the site and not left to lie and rot in the rivers or on the banks. In order to expose the bedrock and other rocky sections of the river, removal of sand from the riverbed should be considered.

Current distribution map

Undated records;  pre-1996;  1996 to 2002;  2003 to present