Teleophrys tumidus

Teleophrys tumidus is a spider crab of the family Mithracidae ^[1], described in 1889 by Cano under the name Mitraculus tumidus, with its type locality at Paita in northern Peru ^[2]. The Peruvian decapod catalogue treats it as a rocky-shore species known from Zorritos to Independencia Bay and from the Lobos de Afuera islands, and gives it as endemic to Peru following Garth ^[3].

In the older literature it was confused with Teleophrys cristulipes, a species of the American Pacific that the Peruvian catalogue places from Baja California to the Galapagos, and Rathbun distinguished it from that species in 1925 ^[2],[3]. Almost nothing has been published on its biology: this account rests on taxonomic descriptions and the Peruvian catalogue, and leaves blank whatever no source supports ^[3].

It is a modest-sized spider crab: the male Rathbun measured, dredged in Sechura Bay, had a carapace 17.8 mm long and 19 mm wide including the spines ^[2]. The carapace is proportionally longer and more triangular than that of Teleophrys cristulipes, with a more pronounced lateral angle, more granules and fewer tubercles and spines ^[2].

Each anterolateral margin of the carapace bears only 2 spines, one at the lateral angle and one in front of it; the anterior branchial spine and the hepatic spine found in Teleophrys cristulipes are tubercles here ^[2]. The front is less than 2 times as broad as long, and a narrow slit lies between the rostral horns ^[2].

The second free article of the antenna is short and stout, less than 2 times as long as its distal width. The walking legs are sturdier than in the related species, and the propodus has a lobe on the posterior surface in addition to the upper lobe ^[2]. In the well-developed male the fingers of the claw taper gradually from base to tip ^[2].

For identification it helps to know that the older literature mixed the two species. In 1910 Rathbun assigned to Teleophrys cristulipes specimens from Sechura Bay that he later recognised as Teleophrys tumidus ^[4],[2].

Similar species

• Teleophrys cristulipes: It has 3 branchial spines on the anterolateral margin (rarely 4), a long slender second free antennal article and a single lobe on the propodus of the walking legs ^[2].

The type locality is Paita in northern Peru, and in 1925 Rathbun summarised the range as the Galapagos Islands and northern Peru ^[2]. The 2012 Peruvian catalogue narrows this: it states that Rathbun's Galapagos specimens belong to Teleophrys cristulipes and gives Teleophrys tumidus a range from Zorritos to Independencia Bay and the Lobos de Afuera islands, with records at Zorritos, Paita, Sechura Bay, Lobos de Afuera and Independencia Bay, and considers it endemic to Peru following Garth ^[3].

The confusion with the neighbouring species also affects the map: according to the Peruvian catalogue, the Sechura Bay specimens that Rathbun treated as Teleophrys cristulipes actually belong to Teleophrys tumidus ^[3],[4].

As for habitat, Garth, cited in the Peruvian catalogue, places it on rocky shores from the intertidal down to 18 m depth, over sand and shell-gravel bottoms ^[3]. The Sechura Bay specimens were dredged in 5 to 6 fathoms on 10 April 1907 ^[4],[2].

No data on feeding, reproduction or growth appear in the sources consulted. All that can be said is that among the specimens from Paita gathered by the Hassler expedition there was an ovigerous female, that is, one carrying eggs on her abdomen ^[2].

Peruvian literature places it on rocky coast in the north and centre of the country, from the intertidal to 18 m, with localities at Zorritos, Paita, Sechura Bay, the Lobos de Afuera islands and Independencia Bay (data from the 2012 catalogue) ^[3]. None of the sources indicates restricted or difficult access at those places ^[3].

It is a small crab of little-known habits; its identification is confirmed by the anterolateral spines and leg characters described above ^[2].