Spinipterus, Akama, Alberto & Ferraris, Carl J., 2011

Akama, Alberto & Ferraris, Carl J., 2011, Spinipterus, a new genus of small, spiny catfish (Siluriformes: Auchenipteridae) from the Peruvian Amazon, Zootaxa 2992, pp. 52-60 : 53

Spinipterus , gen. nov.

Type species: Spinipterus acsi , n. sp., by monotypy and original designation.

Diagnosis. A genus of the auchenipterid subfamily Auchenipterinae that is distinguished from all other auchenipterid genera by the following combination of derived features: pectoral- and dorsal-fin spines with four rows of serrations running from base to the tip of the spines ( Figures 1 , 2 A, B); (2) lateral margins of skull roofing bones ornamented with a single row of spines ( Figure 3 ); (3) groove along dorsal midline posterior to dorsal fin, in which the adducted dorsal fin rests. Also the new genus has a unique combination of fin-ray meristics that are summarized as follows: D- II,4-5; P- I,5-6; V- i,5 (i,4 on opposite side); A- iv,16; C- i,7,9,i.

Remarks. Spinipterus acsi is unique in the possession of four rows of serrations running along the length of the spine ( Figures 1 , 2 A, B). In other auchenipterids, and generally in the Siluriformes , the pectoral- and dorsal-fin spines usually have two or fewer rows of serrations which run along the anterior and poster margin of the spines. In some cases, the anterior row of serrations along the spines is flanked by smooth ridges. In Spinipterus acsi , these flanking ridges have serrations that extend perpendicular to the main axis of the spine. Serrated ridges are also found in Parauchenipterus ceratophysus , but in this species the extra rows are irregularly distributed and converge basally towards the anterior row of serrations.

The entire lateral margin of the skull roof is ornamented with a single row of spines, which also are found on the preopercle and posterior cleithral process ( Figure 3 ). Although some auchenipterid catfish possess low tubercles or projections on the surface of cranial bones, no other species possess conical spines or tooth-like projections. Moreover, the distribution of these spines is restricted to the margins of the cranium, a feature that may be unique among siluriforms.

The dorsal midline groove extends immediately posterior the dorsal-fin base and is approximately the same length as the adpressed dorsal fin. This groove accommodates the entire dorsal-fin spine and fin rays, which are unusually short for auchenipterids.

In addition to the features mentioned above, Spinipterus acsi exhibits the following combination of characters that are useful in distinguishing it from other auchenipterids: a posterior cleithral process ornamented with large spines; caudal-fin margin rounded, with fin fold; lateral line straight, not bifurcated on caudal-fin base; adipose-fin base long (see comments on these characters in the Discussion).

Etymology. Spinipterus is derived from spina from the Latin for spine and pterus from the Greek pteros meaning wing, in reference to the serrated nature of fin spines. Gender masculine.

Figures

FIGURE 1. Spinipterus acsi, lateral view, holotype, ANSP 178209, 32 mm SL.

FIGURE 2. Pectoral-fin spine of Spinipterus acsi. A. Anterior view. B. Schematic illustration of cross section of spine. 1. Anterior row of serrations. 2. Posterior row of serrations. 3. Anterodorsal row of serrations. 4. Anteroventral row of serrations.

FIGURE 3. Head of Spinipterus acsi in anterodorsal view.