In the Internet of Things (IoT), domain applications can be achieved by assembling the functionalities of IoT devices, which can be encapsulated as IoT services. A precise and adaptive monitoring at runtime is fundamental to guarantee the health of running IoT service compositions. Current techniques can hardly conduct the monitoring of dependencies prescribed upon IoT services in compositions. Besides, formal methods, like Signal Temporal Logic (STL) and its last extensions, lacks operators to collectively monitor composite IoT services hosted by spatially contiguous IoT devices for their resource usage fluctuation. To mitigate these limitations, this paper proposes a novel Spatial Composite STL (SCSTL), which enhances STL with spatial encoding and composite operators, to achieve a formal and robust monitoring at runtime, for dependencies prescribed among IoT services, and the resource usage fluctuation of spatially distributed IoT devices. Evaluation results show that our SCSTL outperforms the state-of-the-art techniques.